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# Chemistry paper question watch

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1. I recieved a paper today (4th March) to do during work experience (7th-18th March) and I got really stuck on a question.

Here is the question:
Calcium tablets are used for people with calcium deficiency
Calcium tablets contain calcium carbonate (CaCO3)
Calculate the mass of Calcium in each tablet.

I was just wondering if anyone could explain how to do it because I'm pretty stuck. Thank you!!
2. Does it give you the overall mass of the tablet?
3. (Original post by caitlinford3)
Does it give you the overall mass of the tablet?
Yeah. It says each tablet contains 1.25g of CaCO3
4. Work out the RFM (relative formula mass) of the whole compound
CaCO3
O x 3 = 48 C = 12 Ca = 40
so, CaCO3 = 100

Then, divide the ram of the element you're looking for by the whole RFM
so, 40 / 100 = 0.4

Then times this by 100 to get a percentage (it seems pretty pointless dividing it by 100 then times it again by 100, but sometimes they may ask you of something with an RFM of 40 or something so you always should)

0.4 x 100 = 40%

Calcium makes up 40% of the overall mass
5. (Original post by caitlinford3)
Work out the RFM (relative formula mass) of the whole compound
CaCO3
O x 3 = 48 C = 12 Ca = 40
so, CaCO3 = 100

Then, divide the ram of the element you're looking for by the whole RFM
so, 40 / 100 = 0.4

Then times this by 100 to get a percentage (it seems pretty pointless dividing it by 100 then times it again by 100, but sometimes they may ask you of something with an RFM of 40 or something so you always should)

0.4 x 100 = 40%

Calcium makes up 40% of the overall mass
Thank you so much for your help!! I really appreciate it!!

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