Mole Concept

Mole Concept Questions and Answers

 

By understanding the concept of mole concept very well, you can be successful in chemistry course. In order to increase your success, you can examine the following questions and solutions.



1.

What is the molar mass of N2O3 gas?(N:14 O:16)

A) 28 B) 48 C) 56 D) 76 E) 96

 

Solution:

Mole mass: The mass of 1 mole of atom or 1 mole of molecule is called molar mass (MA).

The molar mass is found by multiplying and summing the atomic masses with the number of elements that make up the compound.

N2O3= 2.N + 3.O = 2.14 + 3.16 = 76.

Answer D

 

2.

How many grams is 1 mole of N2O? ( N : 14 O : 16 )

A)28 B) 30 C) 44 D) 56 E) 72

 

Solution:

1 mole of N2O means the mole mass of N2O compound.

The mole mass is found by multiplying and summing the atomic masses of the elements that make up the compound.

N2O = 2.N + O = 2.14 + 16 = 44 g/mol

Answer C

 

3.

How many moles of oxygen atoms does 2 moles of H3PO4 compound contain?
A) 8 B) 6 C) 4 D) 2 E)1

Solution;

We write the first line of the ratio according to the data found in 1 mole of compound.
There are 4 moles of oxygen in 1 mole of H3PO4 compound.

Then;
If there are 4 moles of O in 1 mole H3PO4
2 moles of H3PO4 has x moles of O
________________________________
x=8 moles of O.

Answer A



4.

How many grams of C atoms does 2 moles of C3H8 molecule contain? (C: 12 g/mol)

A) 12 B) 36 C) 48 D) 64 E) 72

Solution;

Firstly, let’s look at the amount of C in 1 mole of C3H8 compound.

There are 36 grams of C in 1 mole of C3H8 compound

1 mole  C3H8            36 grams C contain.

2 mole  C3H8             x gram C contain

_________________________

x=72 grams C

Answer E

 

5.

How many moles is 16g NaOH? ( Na: 23 O: 16 H: 1 )

A) 0,1 B) 0,2 C) 0,3 D) 0,4 E) 0,5

Solution;

1moles NaOH             40 grams

x moles NaOH            16 grams

______________________

x= 0,4 mol NaO

Answer D

 

 

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