What’s on the pH Calculations poster
The rule, 3 worked examples, and the mistake everyone makes.
- pH is the negative logarithm of hydrogen ion concentration.
- pH = −log[H⁺] · Ka = [H⁺][A⁻] ÷ [HA]
- 0.01 M HCl = pH 2
- 0.1 M weak acid, Ka = 1.8×10⁻⁵ = [H⁺] = √(Ka × c) ≈ 1.3×10⁻³, pH 2.87
- Kw at 25°C = 1.0 × 10⁻¹⁴
- Common mistake: Treating a weak acid like a strong one → Using Ka
Buffers: pH = pKa + log([A⁻]/[HA]). A buffer works best when pH is within one unit of pKa.
Questions about the pH Calculations poster
- What’s on the pH Calculations poster?
- The rule, 3 worked examples, and the mistake everyone makes. pH is the negative logarithm of hydrogen ion concentration.; pH = −log[H⁺] · Ka = [H⁺][A⁻] ÷ [HA]; 0.01 M HCl = pH 2; 0.1 M weak acid, Ka = 1.8×10⁻⁵ = [H⁺] = √(Ka × c) ≈ 1.3×10⁻³, pH 2.87; Kw at 25°C = 1.0 × 10⁻¹⁴; Common mistake: Treating a weak acid like a strong one → Using Ka. Buffers: pH = pKa + log([A⁻]/[HA]). A buffer works best when pH is within one unit of pKa.
- Who is the pH Calculations poster for?
- pH Calculations belongs to the Chemistry section rather than to a school year, because physical science is not something one grade owns. Anyone learning general chemistry can pin it up — a beginner, a student mid-course, or someone revising years later.
- When should you use the pH Calculations poster?
- Strong acids dissociate completely. Weak acids need Ka. A wall chart earns its place by being glanceable from where the work is happening, so pH Calculations belongs on the wall where that physical science work actually happens, within glancing distance, rather than filed away.
- What other posters go with pH Calculations?
- Acids & Bases, Atomic Structure and Balancing Equations sit alongside pH Calculations in the Chemistry section. Printed together they make a wall rather than a single sheet, which is how a reference set actually gets used.Acids & BasesAtomic StructureBalancing Equations
- Is the pH Calculations poster free to download and print?
- Yes. pH Calculations downloads as a free PDF with no account, no email and no watermark, like everything else in the Chemistry section. Print as many copies as you like for a home, a classroom, a library or a tutoring group; reselling the file is the only thing the licence rules out.Read the licence
- What size does the pH Calculations poster print at?
- pH Calculations is a vector PDF laid out for US Letter, and prints on A4 with Fit to page — the same file, no separate download. Because every mark on it is drawn rather than photographed, it stays sharp enlarged to A3, A2 or A1 at a copy shop. Colour carries emphasis only, so a greyscale print of pH Calculations loses nothing.Printing guide
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