Question

(a) A student investigates the rate of reaction between calcium carbonate and hydrochloric acid.
The student does the experiment four times and each time uses:
• the same mass of calcium carbonate
• different sizes of calcium carbonate pieces
• a different concentration of hydrochloric acid.
Table 5.1 shows the four experiments, A, B, C and D.

(i) State which experiment has the fastest rate of reaction.
experiment …………………………………………….
(ii) The student measures the rate of reaction by timing how long it takes for the calcium carbonate pieces to disappear.

Suggest the piece of apparatus the student uses to measure a time of 100s.

……………………………………………………………………………………………………………………. 
(b) The student wants to determine the pH of the acid. She puts some universal indicator paper into the acid.
(i) Describe how the student uses the colour of the universal indicator paper to determine the pH of the hydrochloric acid and its relative acidity.
………………………………………………………………………………………………………………………….
………………………………………………………………………………………………………………………….
………………………………………………………………………………………………………………………….

(ii) Suggest the pH of dilute hydrochloric acid.
pH = …………………………………………….

(c) Hydrogen chloride, HCl, dissolves in water to make hydrochloric acid.
(i) Complete the dot-and-cross diagram in Fig. 5.1 to show the bonding in a molecule of hydrogen chloride. 

Only show the outer shell electrons.

(ii) State the name of this type of chemical bonding.

……………………………………………………………………………………………………………………………….
(d) Hydrogen chloride is a gas. Water is a liquid.
Describe the difference in the structure between a liquid and a gas, in terms of particle separation and the motion of the particles.
particle separation ……………………………………………………………………………………………………..
…………………………………………………………………………………………………………………………………
motion ………………………………………………………………………………………………………………………
…………………………………………………………………………………………………………………………………