Question

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. Calcium hydroxide (“slaked lime”) and sulfuric acid react to produce calcium sulfate and water according to the following balanced equation:

Ca(OH)2(aq) + H2SO4(aq) _> CaSO4(s) + 2 H2O(l)

a. How many liters of 0.2 M calcium hydroxide do you need in order to have 6.0 moles of calcium hydroxide?
b. Find the number of moles of sulfuric acid needed to react with 6.0 moles of calcium hydroxide.
c. If the sulfuric acid has a concentration of 0.9 M, how many liters of it are needed to react with 6.0 moles of calcium hydroxide?

Answer 1

For part A, you're given concentration and moles. How can you find volume using that information?

For part B, look at your reaction. How many moles of H2SO4 react with every mole of Ca(OH)2? And if you have 6 moles of Ca(OH)2, how many moles of H2SO4 are required to react it completely?

For part C, you're given concentration once again. Use this value as well as the moles of H2SO4 you found in part B to find volume, just as you did in part A!

Answer 2

@matt101 I missed the unit on moles and stoichochemistry because I had to get my kidney out and as a result of that I'm intensely confused by anything with formulas now.

Is there any chance you could dumb it down a bit more? At this point I'm just desperately trying not to fail.

Answer 3

Sure - do you understand what a mole is?

Answer 4

Isn't a mole a unit of measurement for chemical substance?

Answer 5

Yes, but it's a very specific unit. A mole is that amount of substance required to give you a mass, in grams, that is the same as the mass, in atomic mass units (amu), of one unit of that substance.

I know that explanation is a bit confusing, so let me give you a couple examples.

- The mass of one ATOM of hydrogen is 1 amu. The mass of one MOLE of hydrogen atoms is 1 g.
- The mass of one MOLECULE of H2O is 18 amu. The mass of one MOLE of H2O is 18 g.

The mole is useful because it's a more standard unit - it refers to a specific NUMBER of particles, and that number is called Avogadro's number (6.02 x 10^23). In a mole of anything, there is always 6.02 x 10^23 particles, regardless of what the substance is, which isn't the case if we look at mass instead:

- If you have 18 g of H2O, you have 1 mole of H2O
- If you have 18 g of H, you have 18 moles of H

So we can't use mass to talk about how much of something we have, because how much you have will depend on the identity of the substance. Does that make sense?

Answer 6

In that case would A.) be 30 liters?

Answer 7

@matt101

Answer 8

@matt101

Answer 9

Absolutely right!

Answer 10

Thank you, Matt!!!