To prepare and standrize 100 ml of 0.1 naoh solution using oxalic acid as primary standard........

Procedure in easy and simple way to learn in few minutes

Searching the Web

standardization of NaOH using oxalic acid primary standard procedure

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Reading Web Page

https://courseware.cutm.ac.in/wp-content/uploads/2020/06/Sod…

Here is a clear, step-by-step guide you can learn in minutes:

Preparation and Standardization of 0.1 M NaOH (100 mL) Using Oxalic Acid

Part 1 - Preparation of 0.1 M NaOH (100 mL)

What You Need

NaOH pellets
Distilled water
100 mL volumetric flask
Weighing balance
Beaker and glass rod

How Much NaOH to Weigh?

Formula: Mass = Molarity × Volume (L) × Molar mass

Molar mass of NaOH = 40 g/mol
Mass = 0.1 × 0.1 × 40 = 0.4 g

Steps

Weigh 0.4 g of NaOH pellets on a watch glass (quickly - NaOH absorbs moisture from air).
Dissolve the pellets in a small amount of distilled water in a beaker. Stir well.
Allow the solution to cool to room temperature (dissolving NaOH generates heat).
Transfer the solution carefully into a 100 mL volumetric flask.
Rinse the beaker 2-3 times with distilled water and add the washings to the flask.
Add distilled water up to the 100 mL mark (bottom of the meniscus).
Stopper and mix well by inverting the flask several times.

Note: This is an approximate (rough) solution. Its exact concentration is determined by standardization.

Part 2 - Standardization of NaOH Using Oxalic Acid

Why Oxalic Acid?

Oxalic acid dihydrate (H₂C₂O₄ · 2H₂O) is a primary standard because it is:

Pure and stable
Has a known molecular weight (126.07 g/mol)
Easy to weigh accurately

The Chemical Reaction

$$\text{H}_2\text{C}_2\text{O}_4 + 2\text{NaOH} \rightarrow \text{Na}_2\text{C}_2\text{O}_4 + 2\text{H}_2\text{O}$$

1 mole of oxalic acid reacts with 2 moles of NaOH
So: n-factor of oxalic acid = 2 (diprotic acid)

How Much Oxalic Acid to Weigh?

To make 100 mL of 0.05 M oxalic acid (equivalent to 0.1 N, which matches 0.1 N NaOH):

Mass = 0.05 × 0.1 × 126.07 = 0.63 g

Weigh approximately 0.63 g of oxalic acid dihydrate.

Equipment Needed

Item	Purpose
Burette (50 mL)	To hold NaOH solution
Pipette (10 mL)	To measure oxalic acid
Conical flask (250 mL)	Titration vessel
Phenolphthalein indicator	To detect endpoint
White tile	To see color change clearly

Steps for Standardization (Titration)

Setting up:

Rinse the burette with distilled water, then rinse with a little NaOH solution. Fill the burette with NaOH solution. Note the initial burette reading.
Rinse the pipette with oxalic acid solution. Pipette out exactly 10 mL of the standard oxalic acid solution into a conical flask.

Titrating:

Add 2-3 drops of phenolphthalein indicator to the flask. Solution remains colorless.
Run NaOH from the burette slowly into the oxalic acid, swirling constantly.
As you approach the endpoint, add NaOH drop by drop.
The endpoint is reached when a faint permanent pink color appears and does not disappear for at least 30 seconds.
Note the final burette reading.

Repeat: Do the titration at least 3 times to get concordant readings (readings within 0.1 mL of each other).

Part 3 - Calculation

Volume of NaOH used = Final reading - Initial reading = V mL (average of concordant readings)

Using the formula:

$$M_1 V_1 = M_2 V_2 \times \text{(ratio from equation)}$$

Or equivalently (normality formula):

$$N_1 V_1 = N_2 V_2$$

Where:

N₁ = Normality of oxalic acid = 0.1 N
V₁ = Volume of oxalic acid = 10 mL
N₂ = Normality of NaOH = ?
V₂ = Volume of NaOH used from burette

$$N_{\text{NaOH}} = \frac{N_1 \times V_1}{V_2} = \frac{0.1 \times 10}{V_2}$$

Example: If you used 9.8 mL of NaOH: $$N_{\text{NaOH}} = \frac{0.1 \times 10}{9.8} = 0.102 \text{ N}$$

Quick Summary Table

Step	Action
1	Weigh 0.4 g NaOH, dissolve, make up to 100 mL
2	Weigh 0.63 g oxalic acid, dissolve, make up to 100 mL
3	Pipette 10 mL oxalic acid into flask
4	Add 2 drops phenolphthalein
5	Titrate with NaOH from burette
6	Endpoint = faint permanent pink
7	Calculate: N(NaOH) = (0.1 × 10) / V(NaOH used)

Key Points to Remember

NaOH is hygroscopic - weigh fast and store in a closed bottle
Always use fresh distilled water (CO₂-free preferred)
Phenolphthalein turns pink in base - endpoint is the first permanent pink
Repeat titration 3 times and use the average volume
The standardized NaOH concentration may differ slightly from 0.1 M - that is normal and expected

Create a printable quick reference card for this procedure

Reading File

Running Command

ls -la /home/daytona/workspace/ 2>/dev/null || echo "workspace empty or not found"

Running Command

mkdir -p /home/daytona/workspace/naoh-card && python3 -c "from reportlab.lib import colors; print('reportlab ok')"

Writing File

~/naoh-card/generate_card.py

from reportlab.lib.pagesizes import A4
from reportlab.lib import colors
from reportlab.lib.units import cm
from reportlab.pdfgen import canvas
from reportlab.lib.styles import getSampleStyleSheet, ParagraphStyle
from reportlab.platypus import Paragraph
from reportlab.lib.enums import TA_CENTER, TA_LEFT

W, H = A4  # 595.27 x 841.89 pts

# ── color palette ──────────────────────────────────────────────
DARK_BLUE   = colors.HexColor("#1a3a5c")
MID_BLUE    = colors.HexColor("#2e6da4")
LIGHT_BLUE  = colors.HexColor("#d6e8f7")
ACCENT      = colors.HexColor("#e74c3c")
GREEN       = colors.HexColor("#27ae60")
LIGHT_GREEN = colors.HexColor("#eafaf1")
YELLOW_BG   = colors.HexColor("#fef9e7")
ORANGE      = colors.HexColor("#e67e22")
GRAY_BG     = colors.HexColor("#f4f6f8")
WHITE       = colors.white
BLACK       = colors.black

def draw_rounded_rect(c, x, y, w, h, r=6, fill_color=WHITE, stroke_color=MID_BLUE, line_width=0.8):
    c.setFillColor(fill_color)
    c.setStrokeColor(stroke_color)
    c.setLineWidth(line_width)
    c.roundRect(x, y, w, h, r, stroke=1, fill=1)

def section_header(c, x, y, w, h, title, bg=DARK_BLUE, text_color=WHITE, fontsize=9.5):
    c.setFillColor(bg)
    c.rect(x, y, w, h, stroke=0, fill=1)
    c.setFillColor(text_color)
    c.setFont("Helvetica-Bold", fontsize)
    c.drawString(x + 6, y + h/2 - fontsize/3, title)

def bullet_row(c, x, y, bullet, text, bullet_color=MID_BLUE, font="Helvetica", fontsize=8, indent=12):
    c.setFillColor(bullet_color)
    c.setFont("Helvetica-Bold", fontsize + 1)
    c.drawString(x + 3, y, bullet)
    c.setFillColor(BLACK)
    c.setFont(font, fontsize)
    c.drawString(x + indent, y, text)

def step_box(c, x, y, w, h, num, title, detail, num_bg=MID_BLUE):
    draw_rounded_rect(c, x, y, w, h, r=5, fill_color=GRAY_BG, stroke_color=MID_BLUE, line_width=0.6)
    # number circle
    c.setFillColor(num_bg)
    c.circle(x + 13, y + h/2, 9, stroke=0, fill=1)
    c.setFillColor(WHITE)
    c.setFont("Helvetica-Bold", 8)
    c.drawCentredString(x + 13, y + h/2 - 3, str(num))
    # title
    c.setFillColor(DARK_BLUE)
    c.setFont("Helvetica-Bold", 8)
    c.drawString(x + 27, y + h - 11, title)
    # detail
    c.setFillColor(colors.HexColor("#444444"))
    c.setFont("Helvetica", 7.5)
    c.drawString(x + 27, y + 3, detail)

def table_row(c, x, y, w, cols, values, fontsize=8, bg=WHITE, bold_first=False):
    c.setFillColor(bg)
    c.rect(x, y, w, 14, stroke=0, fill=1)
    col_x = x + 4
    for i, (cw, val) in enumerate(zip(cols, values)):
        c.setFillColor(BLACK)
        font = "Helvetica-Bold" if (bold_first and i == 0) else "Helvetica"
        c.setFont(font, fontsize)
        c.drawString(col_x + 2, y + 3, str(val))
        col_x += cw

def draw_card(output_path):
    c = canvas.Canvas(output_path, pagesize=A4)
    margin = 1.5 * cm
    usable_w = W - 2 * margin
    mid_x = margin + usable_w / 2

    # ══════════════════════════════════════════════════════
    # HEADER BANNER
    # ══════════════════════════════════════════════════════
    banner_h = 58
    banner_y = H - margin - banner_h
    c.setFillColor(DARK_BLUE)
    c.rect(margin, banner_y, usable_w, banner_h, stroke=0, fill=1)

    # accent stripe
    c.setFillColor(MID_BLUE)
    c.rect(margin, banner_y, 6, banner_h, stroke=0, fill=1)

    c.setFillColor(WHITE)
    c.setFont("Helvetica-Bold", 16)
    c.drawString(margin + 16, banner_y + 33, "NaOH Preparation & Standardization")
    c.setFont("Helvetica", 9)
    c.drawString(margin + 16, banner_y + 17, "0.1 M NaOH  |  100 mL  |  Primary Standard: Oxalic Acid Dihydrate")

    # badge
    c.setFillColor(ACCENT)
    c.roundRect(W - margin - 82, banner_y + 12, 76, 22, 4, stroke=0, fill=1)
    c.setFillColor(WHITE)
    c.setFont("Helvetica-Bold", 8)
    c.drawCentredString(W - margin - 44, banner_y + 20, "QUICK REFERENCE CARD")

    # ══════════════════════════════════════════════════════
    # ROW 1 — two top boxes side by side
    # ══════════════════════════════════════════════════════
    box_y1 = banner_y - 10 - 155
    col_w = usable_w / 2 - 4

    # ── LEFT: Chemicals & Apparatus ──────────────────────
    draw_rounded_rect(c, margin, box_y1, col_w, 155, fill_color=WHITE, stroke_color=MID_BLUE)
    section_header(c, margin, box_y1 + 135, col_w, 20, "  CHEMICALS & QUANTITIES")

    chem_data = [
        ("NaOH pellets",          "0.40 g",   MID_BLUE),
        ("Oxalic acid·2H₂O",     "0.63 g",   GREEN),
        ("Distilled water",        "~200 mL",  MID_BLUE),
        ("Phenolphthalein (ind.)", "2–3 drops",ORANGE),
    ]
    ry = box_y1 + 123
    for name, qty, col in chem_data:
        c.setFillColor(col)
        c.setFont("Helvetica-Bold", 8)
        c.drawString(margin + 6, ry, qty)
        c.setFillColor(BLACK)
        c.setFont("Helvetica", 8)
        c.drawString(margin + 58, ry, name)
        ry -= 13

    c.setStrokeColor(LIGHT_BLUE)
    c.setLineWidth(0.5)
    c.line(margin + 6, ry + 7, margin + col_w - 6, ry + 7)

    c.setFillColor(DARK_BLUE)
    c.setFont("Helvetica-Bold", 7.5)
    c.drawString(margin + 6, ry - 5, "KEY APPARATUS:")
    apparatus = ["100 mL volumetric flask", "50 mL burette", "10 mL pipette",
                 "250 mL conical flask",    "White tile",    "Analytical balance"]
    ax, ay = margin + 6, ry - 17
    for i, ap in enumerate(apparatus):
        col_offset = 0 if i % 2 == 0 else col_w // 2
        row_y = ay - (i // 2) * 11
        c.setFillColor(MID_BLUE)
        c.circle(margin + 6 + col_offset + 3, row_y + 3, 2, stroke=0, fill=1)
        c.setFillColor(BLACK)
        c.setFont("Helvetica", 7.5)
        c.drawString(margin + 6 + col_offset + 8, row_y, ap)

    # ── RIGHT: Chemical Reaction ──────────────────────────
    rx0 = margin + col_w + 8
    draw_rounded_rect(c, rx0, box_y1, col_w, 155, fill_color=WHITE, stroke_color=GREEN)
    section_header(c, rx0, box_y1 + 135, col_w, 20, "  CHEMICAL REACTION", bg=GREEN)

    c.setFillColor(LIGHT_GREEN)
    c.roundRect(rx0 + 6, box_y1 + 95, col_w - 12, 34, 4, stroke=0, fill=1)
    c.setFillColor(DARK_BLUE)
    c.setFont("Helvetica-Bold", 8.5)
    c.drawCentredString(rx0 + col_w/2, box_y1 + 117, "H\u2082C\u2082O\u2084  +  2 NaOH")
    c.setFillColor(ACCENT)
    c.setFont("Helvetica-Bold", 10)
    c.drawCentredString(rx0 + col_w/2, box_y1 + 104, "\u2192  Na\u2082C\u2082O\u2084  +  2 H\u2082O")

    facts = [
        ("Molar mass NaOH",          "40.00 g/mol"),
        ("Molar mass Oxalic·2H\u2082O", "126.07 g/mol"),
        ("Reaction ratio",            "1 mol acid : 2 mol NaOH"),
        ("Equivalent factor (n)",     "2  (diprotic acid)"),
        ("Indicator",                 "Phenolphthalein"),
    ]
    fy = box_y1 + 86
    for label, val in facts:
        c.setFillColor(colors.HexColor("#555555"))
        c.setFont("Helvetica", 7.5)
        c.drawString(rx0 + 6, fy, label + ":")
        c.setFillColor(DARK_BLUE)
        c.setFont("Helvetica-Bold", 7.5)
        c.drawRightString(rx0 + col_w - 6, fy, val)
        fy -= 12

    # endpoint note
    c.setFillColor(YELLOW_BG)
    c.roundRect(rx0 + 6, box_y1 + 4, col_w - 12, 20, 3, stroke=0, fill=1)
    c.setFillColor(ORANGE)
    c.setFont("Helvetica-Bold", 8)
    c.drawString(rx0 + 10, box_y1 + 11, "ENDPOINT: Faint permanent PINK  (30 sec stable)")

    # ══════════════════════════════════════════════════════
    # ROW 2 — PART A steps
    # ══════════════════════════════════════════════════════
    row2_y = box_y1 - 12 - 125
    draw_rounded_rect(c, margin, row2_y, usable_w, 125, fill_color=WHITE, stroke_color=MID_BLUE)
    section_header(c, margin, row2_y + 105, usable_w, 20, "  PART A — PREPARATION OF 0.1 M NaOH (100 mL)")

    steps_a = [
        ("Weigh",    "Weigh 0.40 g NaOH pellets quickly (hygroscopic!)"),
        ("Dissolve", "Dissolve in ~30 mL distilled water in a beaker; stir"),
        ("Cool",     "Let solution cool to room temperature"),
        ("Transfer", "Pour into 100 mL volumetric flask; rinse beaker 2-3×"),
        ("Make up",  "Add distilled water to the 100 mL mark (bottom meniscus)"),
        ("Mix",      "Stopper the flask; invert 10× to homogenize"),
    ]
    sw = usable_w / 3 - 4
    sx, sy = margin + 4, row2_y + 92
    for i, (title, detail) in enumerate(steps_a):
        col = i % 3
        row = i // 3
        bx = margin + 4 + col * (sw + 4)
        by = sy - row * 38 - 34
        step_box(c, bx, by, sw, 33, i + 1, title, detail, num_bg=MID_BLUE)

    # ══════════════════════════════════════════════════════
    # ROW 3 — PART B steps
    # ══════════════════════════════════════════════════════
    row3_y = row2_y - 12 - 125
    draw_rounded_rect(c, margin, row3_y, usable_w, 125, fill_color=WHITE, stroke_color=GREEN)
    section_header(c, margin, row3_y + 105, usable_w, 20, "  PART B — STANDARDIZATION (TITRATION)", bg=GREEN)

    steps_b = [
        ("Prepare std", "Dissolve 0.63 g oxalic acid in water → 100 mL flask"),
        ("Fill burette", "Rinse burette with NaOH; fill; note initial reading"),
        ("Pipette",      "Pipette 10 mL oxalic acid into conical flask"),
        ("Indicator",    "Add 2-3 drops phenolphthalein (solution = colorless)"),
        ("Titrate",      "Run NaOH slowly; swirl; add drop-by-drop near end"),
        ("Repeat",       "Repeat 3× for concordant readings (within 0.1 mL)"),
    ]
    for i, (title, detail) in enumerate(steps_b):
        col = i % 3
        row = i // 3
        bx = margin + 4 + col * (sw + 4)
        by = row3_y + 92 - row * 38 - 34
        step_box(c, bx, by, sw, 33, i + 1, title, detail, num_bg=GREEN)

    # ══════════════════════════════════════════════════════
    # ROW 4 — Calculation box + Key reminders side by side
    # ══════════════════════════════════════════════════════
    row4_y = row3_y - 12 - 110
    calc_w = usable_w * 0.54
    tip_w  = usable_w - calc_w - 8

    # Calculation box
    draw_rounded_rect(c, margin, row4_y, calc_w, 110, fill_color=WHITE, stroke_color=DARK_BLUE, line_width=1.2)
    section_header(c, margin, row4_y + 90, calc_w, 20, "  CALCULATION FORMULA", bg=DARK_BLUE)

    c.setFillColor(LIGHT_BLUE)
    c.roundRect(margin + 6, row4_y + 56, calc_w - 12, 28, 4, stroke=0, fill=1)
    c.setFillColor(DARK_BLUE)
    c.setFont("Helvetica-Bold", 10)
    c.drawCentredString(margin + calc_w/2, row4_y + 71, "N\u2081V\u2081  =  N\u2082V\u2082")
    c.setFont("Helvetica", 8)
    c.setFillColor(colors.HexColor("#333333"))
    c.drawCentredString(margin + calc_w/2, row4_y + 59, "N(NaOH)  =  (0.1 \u00d7 10) / V(NaOH used)")

    c.setFillColor(BLACK)
    c.setFont("Helvetica-Bold", 8)
    c.drawString(margin + 8, row4_y + 48, "Where:")
    vars_data = [
        ("N\u2081", "Normality of oxalic acid = 0.1 N"),
        ("V\u2081", "Volume of oxalic acid = 10 mL"),
        ("N\u2082", "Normality of NaOH = ? (to find)"),
        ("V\u2082", "Volume of NaOH used from burette (mL)"),
    ]
    vy = row4_y + 37
    for sym, meaning in vars_data:
        c.setFillColor(MID_BLUE)
        c.setFont("Helvetica-Bold", 8)
        c.drawString(margin + 10, vy, sym)
        c.setFillColor(BLACK)
        c.setFont("Helvetica", 7.5)
        c.drawString(margin + 26, vy, "= " + meaning)
        vy -= 10

    c.setFillColor(YELLOW_BG)
    c.roundRect(margin + 6, row4_y + 4, calc_w - 12, 14, 3, stroke=0, fill=1)
    c.setFillColor(ORANGE)
    c.setFont("Helvetica-Bold", 7.5)
    c.drawCentredString(margin + calc_w/2, row4_y + 9, "Example:  V(NaOH) = 9.8 mL  →  N(NaOH) = (0.1×10)/9.8 = 0.102 N")

    # Key reminders box
    tip_x = margin + calc_w + 8
    draw_rounded_rect(c, tip_x, row4_y, tip_w, 110, fill_color=WHITE, stroke_color=ORANGE, line_width=1.2)
    section_header(c, tip_x, row4_y + 90, tip_w, 20, "  KEY REMINDERS", bg=ORANGE, text_color=WHITE)

    tips = [
        ("\u26a0", "NaOH is hygroscopic - weigh fast!"),
        ("\u26a0", "Use CO\u2082-free distilled water"),
        ("\u2714", "Read burette at bottom of meniscus"),
        ("\u2714", "3 concordant readings (within 0.1 mL)"),
        ("\u2714", "Endpoint = faint pink, stable 30 s"),
        ("\u2714", "Standardized molarity may differ from 0.1"),
    ]
    ty = row4_y + 80
    for icon, tip in tips:
        ico_col = ACCENT if icon == "\u26a0" else GREEN
        c.setFillColor(ico_col)
        c.setFont("Helvetica-Bold", 9)
        c.drawString(tip_x + 6, ty, icon)
        c.setFillColor(BLACK)
        c.setFont("Helvetica", 7.5)
        c.drawString(tip_x + 18, ty, tip)
        ty -= 12

    # ══════════════════════════════════════════════════════
    # FOOTER
    # ══════════════════════════════════════════════════════
    footer_y = row4_y - 10
    c.setStrokeColor(DARK_BLUE)
    c.setLineWidth(0.5)
    c.line(margin, footer_y, W - margin, footer_y)
    c.setFillColor(colors.HexColor("#888888"))
    c.setFont("Helvetica", 7)
    c.drawString(margin, footer_y - 10, "Preparation & Standardization of 0.1 M NaOH using Oxalic Acid Dihydrate as Primary Standard")
    c.drawRightString(W - margin, footer_y - 10, "Analytical Chemistry Quick Reference")

    c.save()
    print(f"PDF saved to {output_path}")

draw_card("/home/daytona/workspace/naoh-card/NaOH_Quick_Reference_Card.pdf")

Running Command

python3 /home/daytona/workspace/naoh-card/generate_card.py

Your printable quick reference card is ready!

NaOH Quick Reference Card

PDF Document · PDF

The A4 card is laid out in 5 clean sections - everything fits on one page:

Section	What's inside
Header banner	Title, concentration, primary standard at a glance
Chemicals & Apparatus	Exact weights/volumes + all glassware needed
Chemical Reaction	Balanced equation, molar masses, n-factor, indicator
Part A - Preparation	6 numbered steps with titles and details
Part B - Standardization	6 numbered titration steps
Calculation formula	N₁V₁ = N₂V₂ with worked example + key reminders

Print at 100% on A4 paper (no scaling). Color printing gives the best result but it reads fine in black-and-white too.

To estimation of barium sulfate...... procedure flash card chemical with h2so4 and bacl2

Writing File

~/naoh-card/baso4_flashcard.py

from reportlab.lib.pagesizes import A4
from reportlab.lib import colors
from reportlab.lib.units import cm
from reportlab.pdfgen import canvas

W, H = A4

# ── Palette ────────────────────────────────────────────────────
DARK_PURPLE  = colors.HexColor("#3b1f5e")
MID_PURPLE   = colors.HexColor("#6c3fc5")
LIGHT_PURPLE = colors.HexColor("#ede7f6")
TEAL         = colors.HexColor("#00796b")
LIGHT_TEAL   = colors.HexColor("#e0f2f1")
AMBER        = colors.HexColor("#e65100")
AMBER_LIGHT  = colors.HexColor("#fff3e0")
RED          = colors.HexColor("#c0392b")
GREEN        = colors.HexColor("#1b5e20")
LIGHT_GREEN  = colors.HexColor("#e8f5e9")
BLUE         = colors.HexColor("#1565c0")
LIGHT_BLUE   = colors.HexColor("#e3f2fd")
GRAY_BG      = colors.HexColor("#f5f5f5")
DARK_GRAY    = colors.HexColor("#37474f")
WHITE        = colors.white
BLACK        = colors.black

def rrect(c, x, y, w, h, r=6, fill=WHITE, stroke=MID_PURPLE, lw=0.8):
    c.setFillColor(fill)
    c.setStrokeColor(stroke)
    c.setLineWidth(lw)
    c.roundRect(x, y, w, h, r, stroke=1, fill=1)

def sec_hdr(c, x, y, w, h, txt, bg=DARK_PURPLE, fg=WHITE, fs=9.5):
    c.setFillColor(bg)
    c.rect(x, y, w, h, stroke=0, fill=1)
    c.setFillColor(fg)
    c.setFont("Helvetica-Bold", fs)
    c.drawString(x + 7, y + h/2 - fs/3, txt)

def step_pill(c, x, y, num, title, detail, num_bg=MID_PURPLE, bw=None, bh=36):
    if bw is None:
        bw = (W - 2*1.5*cm) / 3 - 4
    rrect(c, x, y, bw, bh, r=5, fill=GRAY_BG, stroke=MID_PURPLE, lw=0.6)
    c.setFillColor(num_bg)
    c.circle(x + 13, y + bh/2, 10, stroke=0, fill=1)
    c.setFillColor(WHITE)
    c.setFont("Helvetica-Bold", 9)
    c.drawCentredString(x + 13, y + bh/2 - 3, str(num))
    c.setFillColor(DARK_PURPLE)
    c.setFont("Helvetica-Bold", 8)
    c.drawString(x + 28, y + bh - 12, title)
    c.setFillColor(DARK_GRAY)
    c.setFont("Helvetica", 7.5)
    c.drawString(x + 28, y + 4, detail)

def draw_baso4_card(out):
    c = canvas.Canvas(out, pagesize=A4)
    mg  = 1.5 * cm
    uw  = W - 2 * mg   # usable width
    half = uw / 2 - 4

    # ══════════════════════════════════════════════════════════
    # HEADER
    # ══════════════════════════════════════════════════════════
    bh = 64
    by = H - mg - bh
    c.setFillColor(DARK_PURPLE)
    c.rect(mg, by, uw, bh, stroke=0, fill=1)
    c.setFillColor(AMBER)
    c.rect(mg, by, 7, bh, stroke=0, fill=1)          # accent stripe

    c.setFillColor(WHITE)
    c.setFont("Helvetica-Bold", 17)
    c.drawString(mg + 18, by + 39, "Estimation of Barium as BaSO\u2084")
    c.setFont("Helvetica", 9)
    c.drawString(mg + 18, by + 23, "Gravimetric Analysis  |  BaCl\u2082 + H\u2082SO\u2084  \u2192  BaSO\u2084\u2193 + 2 HCl")
    c.setFillColor(AMBER)
    c.roundRect(W - mg - 90, by + 14, 84, 22, 4, stroke=0, fill=1)
    c.setFillColor(WHITE)
    c.setFont("Helvetica-Bold", 7.5)
    c.drawCentredString(W - mg - 48, by + 22, "GRAVIMETRIC FLASHCARD")

    # ══════════════════════════════════════════════════════════
    # ROW 1 — Principle + Chemicals side by side
    # ══════════════════════════════════════════════════════════
    r1y = by - 10 - 115
    # LEFT – Principle
    rrect(c, mg, r1y, half, 115, fill=LIGHT_PURPLE, stroke=MID_PURPLE)
    sec_hdr(c, mg, r1y + 95, half, 20, "  PRINCIPLE", bg=MID_PURPLE)

    lines = [
        "Ba\u00b2\u207a ions in BaCl\u2082 are precipitated by H\u2082SO\u2084",
        "as insoluble BaSO\u2084 (white precipitate).",
        "Precipitate is filtered, washed, dried,",
        "ignited, and weighed accurately.",
        "Barium % is calculated from precipitate mass.",
    ]
    py = r1y + 82
    for ln in lines:
        c.setFillColor(DARK_PURPLE)
        c.circle(mg + 8, py + 3, 2.2, stroke=0, fill=1)
        c.setFillColor(BLACK)
        c.setFont("Helvetica", 8)
        c.drawString(mg + 14, py, ln)
        py -= 12

    # RIGHT – Chemicals
    rx0 = mg + half + 8
    rrect(c, rx0, r1y, half, 115, fill=WHITE, stroke=TEAL)
    sec_hdr(c, rx0, r1y + 95, half, 20, "  CHEMICALS & APPARATUS", bg=TEAL)

    chems = [
        ("BaCl\u2082 solution",         "~0.5 g/100 mL",   BLUE),
        ("H\u2082SO\u2084 (dil.)",        "1:10 v/v, 5 mL",  RED),
        ("Distilled water",             "for washing",     TEAL),
        ("Whatman No. 42 filter paper", "ashless",         DARK_GRAY),
        ("Crucible (porcelain)",        "pre-ignited",     AMBER),
    ]
    cy = r1y + 83
    for name, qty, col in chems:
        c.setFillColor(col)
        c.setFont("Helvetica-Bold", 7.5)
        c.drawString(rx0 + 6, cy, qty)
        c.setFillColor(BLACK)
        c.setFont("Helvetica", 7.5)
        c.drawString(rx0 + 80, cy, name)
        cy -= 12

    c.setFillColor(AMBER_LIGHT)
    c.roundRect(rx0 + 6, r1y + 4, half - 12, 14, 3, stroke=0, fill=1)
    c.setFillColor(AMBER)
    c.setFont("Helvetica-Bold", 7.5)
    c.drawCentredString(rx0 + half/2, r1y + 9, "Also: Muffle furnace, analytical balance, desiccator")

    # ══════════════════════════════════════════════════════════
    # ROW 2 — Balanced Equation + MW data
    # ══════════════════════════════════════════════════════════
    r2y = r1y - 10 - 58
    rrect(c, mg, r2y, uw, 58, fill=LIGHT_BLUE, stroke=BLUE, lw=1.2)
    sec_hdr(c, mg, r2y + 38, uw, 20, "  BALANCED EQUATION & MOLAR MASSES", bg=BLUE)

    c.setFillColor(DARK_PURPLE)
    c.setFont("Helvetica-Bold", 12)
    c.drawCentredString(W/2, r2y + 24, "BaCl\u2082  +  H\u2082SO\u2084    \u27f6    BaSO\u2084\u2193  +  2 HCl")
    c.setFillColor(BLUE)
    c.setFont("Helvetica", 8)
    c.drawCentredString(W/2 - 90, r2y + 11, "208.23 g/mol")
    c.drawCentredString(W/2 - 10, r2y + 11, "98.08 g/mol")
    c.drawCentredString(W/2 + 80, r2y + 11, "233.39 g/mol  \u2190 weighed")

    # ══════════════════════════════════════════════════════════
    # ROW 3 — Procedure steps (6 steps, 2 rows × 3 cols)
    # ══════════════════════════════════════════════════════════
    r3y = r2y - 10 - 90
    rrect(c, mg, r3y, uw, 90, fill=WHITE, stroke=DARK_PURPLE, lw=1)
    sec_hdr(c, mg, r3y + 70, uw, 20, "  STEP-BY-STEP PROCEDURE")

    sw = uw / 3 - 4
    steps = [
        ("Dissolve",   "Dissolve BaCl\u2082 sample in ~100 mL distilled water"),
        ("Acidify",    "Add 5 mL dil. H\u2082SO\u2084; heat solution to near boiling"),
        ("Precipitate","White BaSO\u2084 ppt forms; stir; let digest 1 hour"),
        ("Filter",     "Filter hot thro Whatman 42; wash ppt with hot water"),
        ("Dry & Ignite","Dry paper+ppt; ignite at 800\u2013900\u00b0C in muffle furnace"),
        ("Weigh",      "Cool in desiccator; weigh crucible+BaSO\u2084 to 0.0001 g"),
    ]
    for i, (title, detail) in enumerate(steps):
        col = i % 3
        row = i // 3
        bx = mg + 2 + col * (sw + 6)
        bby = r3y + 58 - row * 40
        step_pill(c, bx, bby, i+1, title, detail, num_bg=DARK_PURPLE, bw=sw, bh=34)

    # ══════════════════════════════════════════════════════════
    # ROW 4 — Calculation + Observations side by side
    # ══════════════════════════════════════════════════════════
    r4y = r3y - 10 - 118
    cw = uw * 0.52
    ow = uw - cw - 8

    # Calculation
    rrect(c, mg, r4y, cw, 118, fill=WHITE, stroke=BLUE, lw=1.2)
    sec_hdr(c, mg, r4y + 98, cw, 20, "  CALCULATIONS", bg=BLUE)

    c.setFillColor(LIGHT_BLUE)
    c.roundRect(mg + 6, r4y + 66, cw - 12, 26, 4, stroke=0, fill=1)
    c.setFillColor(BLUE)
    c.setFont("Helvetica-Bold", 9.5)
    c.drawCentredString(mg + cw/2, r4y + 79, "Wt of BaSO\u2084  =  W\u2082 \u2212 W\u2081  (g)")
    c.setFillColor(DARK_GRAY)
    c.setFont("Helvetica", 7.5)
    c.drawCentredString(mg + cw/2, r4y + 68, "W\u2081 = empty crucible wt  |  W\u2082 = crucible + ppt wt")

    c.setFillColor(LIGHT_GREEN)
    c.roundRect(mg + 6, r4y + 38, cw - 12, 24, 4, stroke=0, fill=1)
    c.setFillColor(GREEN)
    c.setFont("Helvetica-Bold", 9.5)
    c.drawCentredString(mg + cw/2, r4y + 50, "% Ba  =  (Wt BaSO\u2084 \u00d7 137.33 / 233.39) \u00d7 (100 / W\u209b)")
    c.setFillColor(DARK_GRAY)
    c.setFont("Helvetica", 7.5)
    c.drawCentredString(mg + cw/2, r4y + 39, "W\u209b = weight of sample taken")

    c.setFillColor(AMBER_LIGHT)
    c.roundRect(mg + 6, r4y + 16, cw - 12, 18, 3, stroke=0, fill=1)
    c.setFillColor(AMBER)
    c.setFont("Helvetica-Bold", 8)
    c.drawCentredString(mg + cw/2, r4y + 22, "Gravimetric Factor = Ba / BaSO\u2084 = 137.33 / 233.39 = 0.5885")

    c.setFillColor(DARK_GRAY)
    c.setFont("Helvetica", 7.5)
    c.drawCentredString(mg + cw/2, r4y + 7, "Molar mass: Ba = 137.33  |  BaSO\u2084 = 233.39  |  BaCl\u2082 = 208.23")

    # Observations / Key Points
    ox = mg + cw + 8
    rrect(c, ox, r4y, ow, 118, fill=WHITE, stroke=AMBER, lw=1.2)
    sec_hdr(c, ox, r4y + 98, ow, 20, "  OBSERVATIONS & KEY POINTS", bg=AMBER, fg=WHITE)

    obs = [
        ("\u2714", "White crystalline precipitate forms", GREEN),
        ("\u2714", "BaSO\u2084 is insoluble in hot/cold water", GREEN),
        ("\u2714", "Precipitate must be digested (aged)", GREEN),
        ("\u26a0", "Avoid excess H\u2082SO\u2084 (co-precipitation)", RED),
        ("\u26a0", "Wash until filtrate is chloride-free", RED),
        ("\u26a0", "Ignite at 800-900\u00b0C; NOT above 1000\u00b0C", RED),
        ("\u2139", "BaSO\u2084 is stable, non-hygroscopic", BLUE),
        ("\u2139", "Cool in desiccator before each weighing", BLUE),
    ]
    ty = r4y + 87
    for icon, tip, col in obs:
        c.setFillColor(col)
        c.setFont("Helvetica-Bold", 9)
        c.drawString(ox + 5, ty, icon)
        c.setFillColor(BLACK)
        c.setFont("Helvetica", 7.5)
        c.drawString(ox + 18, ty, tip)
        ty -= 11

    # ══════════════════════════════════════════════════════════
    # ROW 5 — Sources of error flash strip
    # ══════════════════════════════════════════════════════════
    r5y = r4y - 8 - 34
    rrect(c, mg, r5y, uw, 34, fill=colors.HexColor("#fce4ec"), stroke=RED, lw=1)
    sec_hdr(c, mg, r5y + 14, uw, 20, "  COMMON SOURCES OF ERROR", bg=RED)

    errors = [
        "Co-precipitation of Cl\u207b",
        "Incomplete washing",
        "Incomplete ignition",
        "Hygroscopic gain if not cooled properly",
        "Crucible not pre-ignited / tared",
    ]
    ex = mg + 6
    for err in errors:
        c.setFillColor(RED)
        c.circle(ex + 3, r5y + 6, 2.2, stroke=0, fill=1)
        c.setFillColor(BLACK)
        c.setFont("Helvetica", 7.5)
        tw = c.stringWidth(err, "Helvetica", 7.5)
        c.drawString(ex + 8, r5y + 2, err)
        ex += tw + 20

    # ══════════════════════════════════════════════════════════
    # FOOTER
    # ══════════════════════════════════════════════════════════
    fy = r5y - 10
    c.setStrokeColor(DARK_PURPLE)
    c.setLineWidth(0.5)
    c.line(mg, fy, W - mg, fy)
    c.setFillColor(colors.HexColor("#888888"))
    c.setFont("Helvetica", 7)
    c.drawString(mg, fy - 10, "Estimation of Barium as BaSO\u2084  |  Gravimetric Analysis  |  BaCl\u2082 + H\u2082SO\u2084 \u2192 BaSO\u2084\u2193 + 2HCl")
    c.drawRightString(W - mg, fy - 10, "Analytical Chemistry Quick Reference Card")

    c.save()
    print(f"Saved: {out}")

draw_baso4_card("/home/daytona/workspace/naoh-card/BaSO4_Estimation_Flashcard.pdf")

Running Command

python3 /home/daytona/workspace/naoh-card/baso4_flashcard.py

Your BaSO₄ estimation flashcard is ready!

BaSO4 Estimation Flashcard

PDF Document · PDF

Here is everything packed into one A4 page:

Section	Content
Principle	How Ba²⁺ precipitates as BaSO₄ - 5 bullet points
Chemicals & Apparatus	BaCl₂, H₂SO₄, filter paper, crucible, furnace
Balanced Equation	BaCl₂ + H₂SO₄ → BaSO₄↓ + 2HCl with molar masses
6 Procedure Steps	Dissolve → Acidify → Precipitate → Filter → Ignite → Weigh
Calculations	Wt BaSO₄ = W₂ - W₁, % Ba formula, gravimetric factor 0.5885
Observations & Key Points	8 tips with green/red/blue color coding
Sources of Error	5 common mistakes to avoid (co-precipitation, incomplete washing, etc.)

Print at 100% on A4, preferably in color. It covers the complete gravimetric procedure from start to calculation in a single glance.

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