Question

How many moles are there in 140g nitrogen?
b) how many atoms are there in 140g nitrogen?
(Atomic mass =14)

Answer 1

Answer:

a) 5 moles are in 140g of nitrogen

b) 3.01 x 10^24

Explanation:

a) 3 steps are needed to solve this problem

step 1:

determine how many grams are given in the question,

which in this case is 140

step 2:

calculate the molar mass of the substance

(to calculate molar mass you multiply the atomic mass of an element by the subscript, and if you have more than one element, add all numbers and that is your molar mass)

nitrogen is N2

so you multiply the atomic mass of the nitrogen (which is 14) by the subscript and here it would be 2 (because it's a diatomic molecule) so.

The molar mass of nitrogen is 28

step 3:

Divide step 1 by step 2

140 / 28 = 5

as a conversion factor you'd use this

grams of the substance/ moles of the substance = molar mass of the substance in grams / one mol

140g divided by x = 28g divided by 1 mole

. cross multiply to get

(140g)(1 mole) = (x) (28g)

x = 5 mol

b)

1- the number of atoms in 1 mole is given by Avogadro's number. ( 6.02 x 10^23 )

2- multiply the number of moles by Avogadro's number

No. of atoms in 140g of nitrogen is 5 ( number of moles) * 6.02 x 10^23

=3.01 * 10^24

Answer 2

Given: Given quantity is 140g nitrogen.

To find: We have to find out the number of moles and number of atoms of nitrogen.

Solution:

The molecular mass of nitrogen is 28.

The quantity of nitrogen is 140grm.

Now number of moles is a ratio of mass to molecular mass.

So, number of moles of nitrogen is-

$\frac{140}{28} = 5$

There is 5 moles of nitrogen in 140g nitrogen.

1 mole of nitrogen contain $6.023×10^{23}$ number of atoms.

5 mole of nitrogen will contain-

$6.023×10^{23} \times 5 = 30 \times {10}^{23}$

So, $30×10^{23}$ atoms are present in 140g nitrogen.