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4.1 Acids

4.1 Acids

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Question 87

An environmental technician is investigating the remediation of acidic wastewater containing dilute nitric acid by treating it with successive additions of magnesium oxide.

The technician follows this experimental protocol:

  1. Measure 40 cm3 of the acidic wastewater into an Erlenmeyer flask.
  2. Determine and record the initial pH of the wastewater.
  3. Add a 0.3 g portion of magnesium oxide powder to the flask and agitate the mixture thoroughly.
  4. Estimate the pH of the mixture by placing a drop on universal indicator paper and matching the resulting colour to a standard pH colour chart.
  5. Repeat steps 3 and 4 until the pH reading remains constant.

State one specific improvement to step 4 that would provide a more accurate and precise determination of the pH.

[1]
Markscheme

4.1 Acids Questions

  1. GCSE
  2. /Chemistry
  3. /4.1 Acids

276 exam-style questions on Edexcel GCSE Chemistry 4.1 Acids, covering 4.1.1 Acids, alkalis and the pH scale, 4.1.2 Hydrogen ion concentration and pH, 4.1.3 Dilute and concentrated, weak and strong acids, 4.1.4 Bases, alkalis and the reactions of acids, 4.1.5 Chemical tests for hydrogen and carbon dioxide, 4.1.6 Neutralisation as a reaction of acids with bases, 4.1.7 Preparing soluble salts, and 4.1.8 Solubility rules and preparing insoluble salts. Each one has a worked solution and a mark scheme showing where the marks go.

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