93) If 50 g water is completely decomposed into hydrogen and oxygen, the total mass of
gas obtained will be:
a) 18 g
b) 30 g
c) 36 g
d) 50 g
e. 75 g
Answers
Answer:
H
2
+
2
1
O
2
→H
2
O
Explanation:
11th
Chemistry
Some Basic Concepts of Chemistry
Stoichiometry and Stoichiometric Calculations
How many grams of H2O will ...
CHEMISTRY
How many grams of H
2
O will be formed when 16.0 g H
2
is mixed with 16.0 g O
2
and allowed to react to form water?
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ANSWER
H
2
+
2
1
O
2
→H
2
O
1 mole of H
2
combines with a half mole of O
2
to form one mole of H
2
O.
The molecular weights of H
2
, O
2
and H
2
O are 2 g/mol, 32 g/mol and 18 g/mole respectively.
2 g (1 mole) of H
2
combines with 16 g (half mole) of O
2
to form 18 g (one mole) of H
2
O.
We have 16.0 H
2
is mixed with 16.0g O
2
Out of this, 2.0 H
2
will combine with 16.0g O
2
since oxygen mass is limited.
18 g (one mole) of H
2
O will be obtained.
Given: 50 grams of water is completely decomposed into hydrogen and oxygen.
To find: Total mass of gas obtained
Explanation: The reaction for decomposition of water into hydrogen and oxygen is denoted by this chemical equation:
2H20 ----> 2H2 + O2
This means that n moles of water gives n moles of hydrogen and n/2 moles of oxygen.
Moles of water given= Given mass/ Molar mass
= 50/18
= 2.78 moles
Therefore, moles of hydrogen obtained= 2.78 moles
Mass = Moles * molar mass of hydrogen
= 2.78* 2
= 5.56 grams
Moles of oxygen obtained= 2.78/2 =1.39 moles
Mass = Moles * Molar mass of oxygen
= 1.39*32
= 44.48 grams
Since hydrogen and oxygen are both gases, therefore the total mass of gas is equal to the sum of the masses of hydrogen and oxygen.
Total mass = 5.56+44.48
= 50.04 grams
which is approximately equal to 50 grams.
Therefore, the total mass of gas obtained by decomposing 50 grams of water is (d) 50 grams.