Question

Nitrogen forms five compounds with oxygen in which 1.0 g of nitrogen combines with 0.572,1.14,1.73,2.28 and 2.85 g of oxygen respectively. Show that these figures agree with law of multiple proportion.

Answer 1

Show that the ratios or "proportions" of the number of moles involved in each compound can be expressed as the ratios of small integers.

For example:
1.0/14 = 0.07143 (moles of N)
0.572/16 = 0.03575 (moles of O)
The ratio N/O is 1.998 or (rounding off to 3 figures), 2:1. it corresponds to nitrous oxide, N2O.

The others should round off to molar N:O proportions of
1:1, 1:2, 2:3 and 2:5.

Answer 2

A reaction requires pure anhydrous calcium Sulfate CaSO4 only unidentified hydrate of calcium Sulfate CaSO4.xH2O is available
1-we heat 67.59 g of unknown hydrate until all the water has been driven off. The resulting mass of pure CaSO4 is 53.4g what is the formula of the hydrate and what is its formula weight?
2-Suppose we wish to obtain enough of this hydrate to supply 95.5 g of CaSO4. How many grams should we weight out?