A mixture containing 10 mL of a nitrogen oxide and 30 ml of hydrogen reacts completely to form 10 mL of nitrogen. What is the formula for the nitrogen oxide?

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Answer 1 · 2017-06-02T20:31:07

The molecular formula of the compound is #"N"_2"O"_3#.

Step 1. Summarize the information

#color(white)(l)"N"_x"O"_y +color(white)(ll) "H"_2 → color(white)(m)"N"_2 + "H"_2"O"#
#"10 mL"color(white)(ml)"30 mL"color(white)(m)"10 mL"#

Step 2. Assume that the reaction involves 1 mol of the compound

Then the partially balanced equation is

#"1N"_x"O"_y +"3H"_2 → "1N"_2 + "H"_2"O"#

Step 3. Balance #"N"#

We have 2 atoms of #"N"# on the right, so we need 2 atoms of #"N"# on the left.

∴ #x= 2# and

#"N"_2"O"_y + "3H"_2 → "N"_2 + "H"_2"O"#

Step 4. Balance #"H"#

We have 6 #"H"# on the left, so we need 6 #"H"# on the right.

Put a 3 in front of #"H"_2"O"#.

#"N"_2"O"_y + "3H"_2 → "N"_2 + "3H"_2"O"#

Step 5. Balance #"O"#.

We have 3 #"O"# on the right, so we need 3 #"O"# on the left.

∴ #y = 3# and

#"N"_2"O"_3 + "3H"_2 → "N"_2 + "3H"_2"O"#

The formula of the compound is #"N"_2"O"_3#.