How many grams of hydrogen are necessary to react completely with 50.0 g of nitrogen in the reaction #N_2+3H_2->2NH_3#?

2 Answers

Answer:

10.80 g of #H_2#

Explanation:

As per the equation, let us calculate the mole ratio.

#N_2 + 3H_2 → 2NH_3#

As per the equation one mole of nitrogen reacts with 1 mol of hydrogen.

In terms of mass. 28.01 g of nitrogen needs 3 mol of hydrogen or 6.048 g of hydrogen.

We can set up the ratio;

#"28.01 g of"color(white)(l) N_2# needs #"6.048 g of"color(white)(l) H_2#

#"1 g of" color(white)(l)N_2# needs #6.048/28.01 "g of"color(white)(l) H_2#

#"50.0 g of"color(white)(l)N_2# needs #(6.048 × 50.0)/28.01color(white)(l) "g of"color(white)(l) H_2 = "10.80 g of"color(white)(l) H_2#

Apr 26, 2016

Answer:

See below..

Explanation:

Assume that:
n = number of moles
m = mass of substance
M = molar mass (equivalent to atomic weight on the periodic table)

#n = m -: M#

The mass (m) of #N_2# has been given to you: 50.0 grams.

You first need to find out the molar mass (M) of nitrogen. If you refer to your periodic table, the molar mass (M) of nitrogen is 14.0 g/mol.
Since there are two nitrogens (refer to equation - look carefully), the molar mass of #N_2# in this reaction is 28.0 g/mol.

Now you need to calculate the number of moles (n) for nitrogen. If you refer back to the formula "#n= m -: M#", you need to find n.
The number of moles (n) for nitrogen is:
[#n = 50.0 -: 28.0 #] = 1.785714286 moles.
Note: Don't round it off just yet because this is not the final answer - or you'll get inaccurate answer.

You next step is to determine the number of moles (n) for hydrogen #(3H_2)#.

Since the mole ratio between #N_2 : H_2# is 1 : 3, so,
If 1 mole of #N_2# gives you 3 moles of #H_2#,
then 1.785714286 moles of #N_2# should give you:
[#1.785714286 xx 3#] = 5.357142857 moles of #H_2#.

Now you know the number of moles for #H_2#.

The next step is to find out the molar mass (M) of Hydrogen. If you refer to your periodic table, you know that hydrogen's molar mass is 1.0 g/mol.

Since there are two hydrogens present the molar mass of hydrogen in this reaction is 2.0 g/mol.
(look at equation, carefully - there are 2, not 5 or 6 because the front number is only used for moles).

Your last step is to find out its mass (m).

If you refer back to the formula #n = m -: M#, you need to make (m) as the subject because you are finding the mass.
Once you've make m as the subject, the formula will look #m = n xx M#.

The mass (m) of hydrogen is:
[#m = 5.357142857 xx 2.0#] = 10.7 grams.
Note that: this answer is rounded to 3 significant figures.

Therefore, 10.7 grams of Hydrogen are necessary to fully react with 50.0 grams of Nitrogen.