a) 100 cm3 of 0.1 mol/dm3 of hydrochloric acid was added to 100 cm3 of 0.1 mol/dm3 of sodium hydroxide and a rise in temperature of 4 degrees was observed. If 200 cm3 of 0.1 mol/dm3 of hydrochloric acid and 200 cm3 of 0.1 mol/dm3 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/dm3 of sulfuric acid
2. 5 mol/dm3 of ethanoic acid
3. 2 mol/dm3 of sulfurous acid
4. 2 mol/dm3 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 H3PO4, 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.