Answer Check Please...

A compund contains only hydrogen and nitrogen and is 12.6% hydrogen by mass. A gaseous sample of the compound has desity of 0.925g/L at 690 torr and 110 degrees Celsius. What is the molecular formula of the compound?

My Empirical Formula = H2N
Molecular Formula = H4N2

Thank you :)

Both look good to me.

To determine the molecular formula of a compound, you need to know the empirical formula and the molar mass of the compound.

In this case, you have already determined the empirical formula to be H2N.

To find the molar mass, you need to calculate the molar mass of each element in the empirical formula and add them up. The molar mass of hydrogen (H) is approximately 1 gram per mole, and the molar mass of nitrogen (N) is approximately 14 grams per mole.

So, the molar mass of H2N is:

2(1 g/mol) + 1(14 g/mol) = 2 + 14 = 16 g/mol

Now, to determine the molecular formula, you need the molar mass of the compound. You can calculate the molar mass by dividing the density (in grams per liter) by the molar volume (22.4 L/mol) at STP (standard temperature and pressure).

First, convert the given density of 0.925 g/L to grams per mole. Multiply the density by the molar volume:

0.925 g/L * (1 mole/22.4 L) = 0.0413 moles per liter

Next, convert the temperature of 110 degrees Celsius to Kelvin by adding 273:

110 degrees Celsius + 273 = 383 Kelvin

Now, apply the ideal gas law to determine the molar mass of the compound:

PV = nRT

where:
P = pressure (690 torr)
V = volume (1 liter)
n = number of moles (0.0413 moles)
R = ideal gas constant (0.0821 L*atm/(mol*K))
T = temperature in Kelvin (383 K)

Rearrange the equation to solve for molecular mass (M):

M = (P * V) / (n * R * T)

Substitute the given values:

M = (690 torr * 1 L) / (0.0413 moles * 0.0821 L*atm/(mol*K) * 383 K)

M = 20,900 torr L / (moles * L*atm/(mol*K))

M = 20,900 / (0.0413 * 0.0821 * 383)

M ≈ 1.99

The molar mass of the compound is approximately 1.99 grams per mole.

To determine the molecular formula, divide the molar mass of the compound by the molar mass of the empirical formula:

(1.99 g/mol) / (16 g/mol) ≈ 0.124

The result is approximately 0.124.

Since the molecular formula is a whole-number multiple of the empirical formula, multiply the subscripts in the empirical formula (H2N) by the result:

[H2N]0.124 ≈ H0.248N0.124

Now, round the subscripts to the nearest whole number:

[H2N]0.124 ≈ H0N

Therefore, the resulting molecular formula is HN.

Based on your calculation, the empirical formula (H2N) and the molecular formula (HN) do not match. Double-check your calculations to make sure you haven't made any errors.