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## Homework Statement

a) 100 cm

^{3}of 0.1 mol/dm

^{3}of hydrochloric acid was added to 100 cm

^{3}of 0.1 mol/dm

^{3}of sodium hydroxide and a rise in temperature of 4 degrees was observed. If 200 cm

^{3}of 0.1 mol/dm

^{3}of hydrochloric acid and 200 cm

^{3}of 0.1 mol/dm

^{3}of sodium hydroxide were used, the rise in temperature would be about?

b) Which solution contains the greatest concentration of hydrogen ions?

1. 2 mol/dm

^{3}of sulfuric acid

2. 5 mol/dm

^{3}of ethanoic acid

3. 2 mol/dm

^{3}of sulfurous acid

4. 2 mol/dm

^{3}of phosphoric acid

**2. The attempt at a solution**

a) I put 8 degrees as the answer since there are twice as many moles for each solution, but I was wrong. The correct answer is 4 degrees. Does this mean that enthalpy change is unaffected by the number of moles of the reactants?

b) I put 4 as the answer since its molecular formula is H

_{3}PO

_{4}, thus there are 3 moles of hydrogen ions in one molecule of the acid and multiplying it by the concentration gives me 6 moles of hydrogen ions, the highest, but I was wrong again. The answer is 1. I have no idea.