Matter is neither created nor destroyed in a chemical reaction. Thus, the mass o

Question

Matter is neither created nor destroyed in a chemical reaction. Thus, the mass of the products of a chemical reaction must be equal to the mass of the starting materials. Formally, this concept is called the law of conservation of mass.

A sample of sodium reacts completely with 0.568 kg of chlorine, forming 936 g of sodium chloride. What mass of sodium reacted?

When carbon is burned in air, it reacts with oxygen to form carbon dioxide. When 26.4 g of carbon were burned in the presence of 83.6 g of oxygen, 13.2 g of oxygen remained unreacted. What mass of carbon dioxide was produced?

Explanation / Answer

M.W of Sodium is = 23

M.W of Chlorine = 35.5

amount of chlorine reacted = 0.568 kg

So number of moles of chlorine reacted is = 0.568 / 35.5 = 0.016 mole

To form sodium chloride 1:1 equivalent of sodium and chlorine are required.

So, amount of sodium required is = 0.016 x 23 = 0.368 kg

So, 0.368 kg of sodium is needed for the production of 936 g of sodium chloride.

M.w. of carbon is = 12

M.W. of oxygen is = 16

M.W. of Oxygen molecule O2 = 32

M.W of carbondioxide is = 44

Amount of carbon burned = 26.4 g

Moles of carbon burned is = 26.4 / 12 = 2.2 mole

to form carbondioxide needs 1:2 equivalent of carbon and oxygen

So, oxygen needed is = 2.2 x 2 = 4.4 x 16 = 70.4 g

amount of oxygen reacted is = 83.6-13.2 = 70.4 g

So, amount of carbondioxide is = 70.4 / 16 = 4.4 x 44 = 193.6 g

So, 193.6 g of corbondioxide will form.

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