Four different anhydrous salts, P, Q, R and S, are separately dissolved in equal volumes of water.

The table below shows the starting temperature of the water and the final temperature of the mixture after each salt completely dissolves.

Complete the table:

to show the temperature changes when salt R and salt S dissolve (you must include the $+$ or $-$ sign)
by placing a tick (✓) in the box on the bottom row for the salt that absorbs the most heat energy from the water when it dissolves.

	Salt P	Salt Q	Salt R	Salt S
Starting temperature in °C	22.0	22.0	22.0	22.0
Final temperature in °C	26.4	18.1	28.3	16.2
Temperature change in °C	+4.4	−3.9	.....	.....
Salt that absorbed the most heat energy when it dissolved

Four different anhydrous salts, P, Q, R and S, are separately dissolved in equal volumes of water.

The table below shows the starting temperature of the water and the final temperature of the mixture after each salt completely dissolves.

Complete the table:

to show the temperature changes when salt R and salt S dissolve (you must include the $+$ or $-$ sign)
by placing a tick (✓) in the box on the bottom row for the salt that absorbs the most heat energy from the water when it dissolves.

	Salt P	Salt Q	Salt R	Salt S
Starting temperature in °C	22.0	22.0	22.0	22.0
Final temperature in °C	26.4	18.1	28.3	16.2
Temperature change in °C	+4.4	−3.9	.....	.....
Salt that absorbed the most heat energy when it dissolved

8.2 Heat energy changes in chemical reactions

8.2 Heat energy changes in chemical reactions Questions