Chemical equations Chemistry Problem with Solution

C2H6 + O2 ——-> CO2 + H2O

What is the coefficient of O2 when the above chemical equation is balanced with the smallest integers?

A) 3 B)4 C)7/2 D)7 E)9

Solution;

Chemical equations are balanced according to the principle of “Conservation of atomic number and type”.

In the equation, we take the floor number of the substance, which is crowded in terms of the number of atoms, as 1, and first we balance the atomic numbers in this substance. We usually look at the latest oxygen count.

The equation is balanced as

1C2H6 + 7/2 O2 ——-> 2 CO2 + 3 H2O.

However, the question asks what is the coefficient of O2 when it is balanced with the smallest integers. In other words, he wants all the coefficients in the reaction to be integers. (In other words, he does not want rational numbers in the coefficients.) Then we save the fraction by multiplying the denominator of the fractional number in the reaction with the coefficients of the whole equation.

We multiply the coefficients for this reaction by 2;

2C2H6 + 7 O2 ——-> 4 CO2 + 6 H2O

The answer is D.

Chemical Calculations Chemistry Problem with Solved

Given the balanced equation: 2H2(g) + O2(g) –> 2H2O(l)
How many grams of H2O are formed if 5 mol H2(g) reacts completely with an excess of O2(g)?

The molar mass of H2O is 18.0g/mol.

Solved:

The coefficients in chemical reactions are the number of moles.

If we write the coefficients below the reaction;

2H2(g) + O2(g) –> 2H2O(l)

2 mol 1mol 2mol

5mol ?mol ?mol

5mol 2,5 mol 2mol

1mol H2O 18.0g/mol

5 mol H2O x

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x=90 grams H2o