1) Suppose the mass of the NaOH used in a reaction was doubled. What would you expect to happen to the heat given off by the reaction? Explain your answer.
2)Again, suppose the mass of the NaOH used in a reaction was doubled. What would you expect to happen to the heat given off per mole of NaOH in the reaction? Explain your answer.
I am not sure what the answer would be, however I do think that for question 1 the answer would be more and for question 2 the answer would be less. If I am right could you explain to me why those would be the answers as I do know the why and if I'm wrong explain what the right answer would be?
Thanks
I may be reading the problem wrong but #2 seems to be stated in a peculiar fashion. I think the two questions are different and #2 doesn't follow from #1.
For #1, if q = mass x (delta H/gram) and you double grams, then q must double and the reaction will release more heat.
If I read #2 correctly, it wants to know, not how much heat is evolved if more NaOH is added, but how much heat is evolved per mole. Delta H/mol is a constant is it not so it makes no difference how much NaOH is added, the heat/mol will stay the same.
The heat would remain the same
1) If the mass of NaOH used in a reaction is doubled, you would expect more heat to be given off by the reaction. This is because the heat given off in a chemical reaction is usually directly proportional to the amount of reactant consumed. In this case, since the mass of NaOH is doubled, there are more particles of NaOH available to react, resulting in a larger amount of heat being released.
2) If the mass of NaOH used in a reaction is doubled, the heat given off per mole of NaOH in the reaction would remain the same. This is because the amount of heat given off in a chemical reaction is determined by the molar amount of the reactants involved. When the mass of NaOH is doubled, the number of moles of NaOH also doubles. Therefore, the heat given off per mole of NaOH remains constant.
So, you were correct in thinking that the answer to question 1 would be "more," but incorrect in thinking that the answer to question 2 would be "less." The correct answer is that the heat given off per mole of NaOH in the reaction would stay the same.
To answer both questions, let's start by understanding the concept of molar heat of reaction or enthalpy change. The molar heat of reaction is the amount of heat energy released or absorbed when a certain number of moles of a substance react.
1) If the mass of NaOH used in a reaction is doubled, we would expect the heat given off by the reaction to also increase. This is because the heat energy released during a reaction is directly proportional to the amount of reactant consumed. When the mass of NaOH is doubled, there are now twice as many moles of NaOH available to react. Consequently, the reaction would release twice as much heat energy compared to the original amount.
2) However, the heat given off per mole of NaOH in the reaction would remain the same. The molar heat of reaction is an intrinsic property that represents the heat released per mole of the reactant participating in the reaction. It does not depend on the mass of the reactant used but rather on the nature of the reaction itself. So, even though the total heat released in question 1 doubles, the heat given off per mole of NaOH would not change. The molar heat of reaction would remain constant.
So, your prediction that the answer to question 1 is "more" and the answer to question 2 is "less" is incorrect. The correct answer to question 1 is "more" because the total heat released doubles when the mass of NaOH is doubled. The correct answer to question 2 is "the same" because the molar heat of reaction remains constant regardless of the mass of the reactant used.