Chemistry equivalents help!?

Question

How many equivalents are in the following masses?

a. 42.3g of HNO3

b. 10.5g of Al(OH)3

c. 5.4g of Ca(OH)2

I don't just want the answers I would like to know how to do it too, I know I'm a dork but I want to learn! lol

Answer 1

Equivalents is an odd concept because it depends on the specific reaction involved. Since these are all acids and bases, just calculate the moles of each compound from their masses and molar masses.

HNO3 has only one H+ that can participate in acid base reactions, so the number of equivalents is equal to the number of moles.

Since Al(OH)3 has 3 OH- ions/mole, it will have 3 equivalents/mole. So, calculate the number of moles and multiply that by 3.

For Ca(OH)2, you have 2 OH-/mole, so multiply the number of moles of Ca(OH)2 by 2.

Hope this helps.