AS Level Chemistry (Need help with questions) Watch

CP1992
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#1
Report Thread starter 9 years ago
#1
Hi everyone basically i need help with 7 questions: these are all on moles-mass calculations

1. What mass of magnesium chloride must be taken if it is to contain 10.65g of chloride ions?

2, What mass of aluminium nitrate should be taken if it is to contain 93g of nitrate ions?

3. A sample of hydrated copper sulphate weighs 50g. How many moles of water molecules does it contain?

Write down:

4. The mass of zinc with the same number of atoms as there are hydroxide ions in 12.2g of magnesium hydroxide.

5. The mass of iron which has the same number of atoms as there are nitrate ions in 0.36g of silver nitrate

6. The mass of sulpher dioxide which contains the same number of molecules as there are in 38g of carbon dioxide

7. The mass of water which contains the same number of molecules as there are chloride ions in 24.2g of calcium chloride.

Help is appreciated thanks alot
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SirMasterKey
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#2
Report 9 years ago
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Moles= Mass x Ar

So you need to rearrange that equation to give you it in terms of mass.

1 +2) Then you could work out the number of moles and then knowing the chemical equations use the Stokeyometric(sp) ratio to determine how many grams.

3) Work out the Ar of CuSO4 and so find out the mass of it. Then work out how this differs from the 50 and then work out the Ar of H2O and add as many as needed to get the mass to 50.

4-5) Not too sure.

6) Work out how many molecules of CO2 there are in 38g. Work out the mass of sulphur dioxide from doing the Moles/Ar.

7) See 6 as is the same just with different compounds.
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AnthonyShock
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These types of questions stalk you until the very end! haha
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