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chemistry help please

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Original post by J_riley18
Okay is 74.093 right?


74 is precise enough.

Now work out the relative formula mass of calcium phosphate. Post your answer.
Reply 21
Original post by TeachChemistry
74 is precise enough.

Now work out the relative formula mass of calcium phosphate. Post your answer.


Is 182.234 right for calcium phosphate
Original post by J_riley18
Is 182.234 right for calcium phosphate


No. Look at the formula. There are 3 calcium, 2 phosphorus and 8 oxygen. Make sure you can see how this is the case and give a revised answer.
Reply 23
Original post by TeachChemistry
No. Look at the formula. There are 3 calcium, 2 phosphorus and 8 oxygen. Make sure you can see how this is the case and give a revised answer.


Is 310 right?
(edited 6 years ago)
Reply 24
Original post by TeachChemistry
No. Look at the formula. There are 3 calcium, 2 phosphorus and 8 oxygen. Make sure you can see how this is the case and give a revised answer.


Is 310 right?
Original post by J_riley18
Is 310 right?


Yes.

Now use the equation below to work out the moles of calcium hydroxide you have in 5 g

Moles X relative formula mass = mass
Reply 26
Original post by TeachChemistry
Yes.

Now use the equation below to work out the moles of calcium hydroxide you have in 5 g
Moles X relative formula mass = mass


Is 370 g/mol correct
Original post by J_riley18
Is 370 g/mol correct


You need to work out the moles. You have the mass and you have the relative formula mass from a few posts back. You need to rearrange the equation I have (hopefully) reminded you of.

Try again.
(edited 6 years ago)
Reply 28
Original post by TeachChemistry
You need to work out the moles. You have the mass and you have the relative formula mass from a few posts back. You need to rearrange the equation I have (hopefully) reminded you of.

Try again.


Is 1.34 mols correct
Original post by J_riley18
Is 1.34 mols correct


I cannot see where this number comes from.

You have 5 g and correctly said that the relative formula mass was 74.

Think again.
Reply 30
Original post by TeachChemistry
I cannot see where this number comes from.

You have 5 g and correctly said that the relative formula mass was 74.

Think again.

I did 5g/mol × 74 = 370 is that right?
Original post by J_riley18
I did 5g/mol × 74 = 370 is that right?


No. Here's a worked answer because it is bedtime for me now. Make sure you follow it through. Ask tomorrow if unsure.
>mfw undergraduate chemistry

This would have been a standard question when I was 14/15 years old

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