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The mole concept questions

Hello!
Please, can you explain to me how to solve this questions? I really don't understand!
Thank you in advance!

1) How many oxygen atoms are present in 1.5 moles of copper(II) sulfate pentahydrate, CuSO₄·5H₂O?

2)Which of the following contains the same number of ions as twice the value of Avogadro’s constant?
A)0.5 mol NaBr
B)1.0 mol Li2O
C)1.0 mol CaO
D)0.5 mol MgI2

3) How many individual ions does one mole of aluminium carbonate contain?

4)Silver oxide, Ag₂O, can be decomposed to silver metal, Ag, plus oxygen gas, O₂. How many molecules oxygen gas will form when 4.64 g of solid silver oxide is decomposed? The formula mass of silver oxide is 231.72 gmol^-1.

5)How many moles of CO₂ are produced when 1.0 mol of KMnO₄, 5.0 mol of H₂C₂O₄, and 3.0 mol of H₂SO₄ are mixed?
2KMnO₄ + 5H₂C₂O₄ + 3H₂SO₄

K₂SO₄ + 2MnSO₄ + 10CO₂ + 8H₂O
o0

The definitions of Avogadro's constant (number) are:

1 mole = 6.02 x 10²³ particles of any substance.

The mass of 1 mol of any species has a mass equal to the relative mass expressed in grams.

Reply 1

Infraspecies

1.

How many atoms of O in the formula?
How many atoms is in one mole?
How many moles do you have?
Multiply all above together for answer.

2.

How many ions in the formula?
How many moles of the compound?
How much is a mole?
Multiply the above together.
Is this number the same as twice Avogadro's constant?

3.

How many ions does aluminium carbonate contain?
The answer is that number times Avogadro's number.

4.

n=m/Mr

Look at the ratio Ag₂O ---> 2Ag + 1/2 (O₂)

5.

Which is the limiting number of moles of reactants?
What proportion do you have compared to what you need?
All of the product amounts will scale to that proportion.

Reply 2

Sofya

Original post by Infraspecies

n=m/Mr

Look at the ratio Ag₂O ---> 2Ag + 1/2 (O₂)

I don't understand how to use formula mass in order to figure out molecules of oxygen ( Please, maybe you can write me how should I do this? I just can't understand it so far!!! Thank you very much

Reply 3

Infraspecies

Original post by Sofya

I don't understand how to use formula mass in order to figure out molecules of oxygen ( Please, maybe you can write me how should I do this? I just can't understand it so far!!! Thank you very much

You have the mass of reactant.
Work out how many moles there are using the formula mass and the mass and the equation I gave you, which you should already know.
Look at the reaction ratio.
Scale the number of moles of product to oxygen gas.
Work out the moles of oxygen gas present.
Times this by Avogadro's number to work out the number of oxygen molecules.