In an investigation to study neutralisation, a student adds small portions of solid calcium hydroxide, Ca(OH)2\text{Ca(OH)}_2Ca(OH)2, to 50 cm3 of dilute hydrochloric acid, HCl(aq)\text{HCl}(\text{aq})HCl(aq), in a beaker and records the pH after each addition.
The method used is:
Step 1: Measure 50 cm3 of dilute hydrochloric acid into a beaker.
Step 2: Add 0.15 g of calcium hydroxide powder to the beaker.
Step 3: Measure and record the pH of the mixture.
Step 4: Repeat Steps 2 and 3 until the pH remains constant.
State one action the student must perform immediately after adding the calcium hydroxide in Step 2, but before measuring the pH in Step 3, to ensure that the reaction is complete.
Practise Edexcel GCSE Chemistry Acids with exam-style questions for Foundation and Higher tier. 276 questions, matched to the Edexcel GCSE Chemistry (1CH0) specification and written in Paper 1 and Paper 2 style. Every question includes a full worked solution and mark scheme, so you can see where marks are awarded rather than just whether you got the answer right.
