Answered

MULTIPLE CHOICE
A sample of a pure ionic compound has a mass of 2.00 g. If 0.72 g of the sample is determined to be made up of calcium, what is the formula of the compound?

A. CaO
B. CaF2
C. CaS
D. CaCl2
E. CaSe
F. CaBr2

Answer :

barnuts

What we can actually do is to find the number of moles of Ca.

moles Ca = 0.72 g / (40.08 g/mol) = 0.018 mol

 

From the given choices, we can all see that there are 1 mol of compound per 1 mole of Ca. Therefore the actual moles of compound is also 0.018 mol. From this, calculate the mass and the answer is the one which will give 2 g.

 

Answer:

D. CaCl2

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