a certain anesthetic contains 64.9% C, 13.5% H, and 21.6% O by mass. at 120 deg Celsius & 750 mmHg, 1.00 L of the gaseous compound has a mass of 2.30g. what is the molecular formula of the compound? PLEASE HELP! THANKYOU!

You need to use the % information to determine the empirical formula of the compound first.

The empirical formula is the simplest ratio of atoms in the molecule.

Then use the rest of the data to determine moles of gas, and use this to determine molar mass of gas...

Empirical formula calculations:

Assume you have 100 g, calculate the moles of each atom in the 100 g

moles = mass / molar mass
molar mass C = 12.01 g/mol
molar mass H = 1.008 g/mol
molar mass O = 16.00 g/mol

C = 64.9 % = 64.6 g
H = 13.5 % = 13.5 g
O = 21.6 % = 21.6 g

moles C = 64.6 g / 12.01 g/mol = 5.38 mol
moles H = 13.5 g / 1.008 g/mol = 13.39 mol
moles O = 21.6 g / 16.00 g/mol = 1.35 mol

So ratio of C : H : O
is 5.38 mol : 13.39 mol : 1.35 mol

Divide each number in the ratio by the lowest number to get the simplest whole number ratio

(5.38 / 1.35) : (13.39 / 1.35) : (1.35 / 1.35)

4 : 10 : 1

empirical formula is
C4H10O

Finding moles and molar mass calcs

Now, you know that at 120 deg C and 750 mmHg that 1.00L compound weighs 2.30 g.

We can use this information to determine the molar mass of the gas after first working out how many moles the are in the 1.00 L

PV = nRT
P = pressure = 750 mmHg
V = volume = 1.00 L
n = moles (unknown)
T = temp in Kelvin (120 deg C = (273.15 + 120) Kelvin)
- T = 393.15 Kelvin
R = gas constant, which is 62.363 mmHg L K^-1 mol^-1 (when your P is in mmHg and volume is in L)

n = PV / RT
n = (750 mmHg x 1.00 L) / (62.363mmHg L K^-1 mol^-1 x 393.15 K)
n = 0.03059 moles of gas

We know moles = 0.03509 and mass = 2.30 g
So we can work out molar mass of the gas

moles = mass / molar mass
Therefore molar mass = mass / moles
molar mass = 2.30 g / 0.03059 mol
= 75.19 g/mol

Determine molecular formula

So empirical formula is C4H10O
molar mass = 75.19 g/mol

To find the molecular formula you divide the molar mass by the formula weight of the empirical formula...
This tells you how many times the empirical formula fits into the molecular formula. Tou then multiply every atom in the empirical formula by this number

formula weight C4H10O = 74.12 g/mol

Divide molar mass by formula weight empirical
75.15 g/mol / 74.12 g/mol
= 1
(It doesn't matter that the number don't quite match, they rarely do in this type of calc (although I could have made a slight error somewhere) but the numbers are very close, so we can say 1.)

The empirical formula only fits into the molar mass once,

molecular formula thus = empirical formula

C4H10O

Therefore, the molecular formula of the compound is C4H10O.

I hope my answer has come to your help. Thank you for posting your question here in Brainly. We hope to answer more of your questions and inquiries soon. Have a nice day ahead!

Eduard22sly Eduard22sly · Answer 2 · 2022-02-10T12:54:47+01:00

The molecular formula of the compound is C₄H₁₀O

Determination of the mole of the compound

Volume (V) = 1L
Temperature (T) = 120 ˚C = 120 + 273 = 393 K
Pressure (P) = 750 mmHg = 750 / 760 = 0.987 atm
Gas constant (R) = 0.0821 atm.L/Kmol
Number of mole (n) =?

The number of mole can be obtained as by using the ideal gas equation as illustrated below:

n = PV / RT

n = (0.987 × 1) / (0.0821 × 393)

n = 0.0306 mole

How to determine the molar mass

Mole = 0.0306 mole
Mass = 2.30 g
Molar mass =?

Molar mass = mass / mole

Molar mass = 2.30 / 0.0306

Molar mass = 75.16 g/mol

How to determine the empirical formula

Carbon (C) = 64.9%
Hydrogen (H) = 13.5%
Oxygen (O) = 21.6%

Empirical formula =?

Divide by their molar mass

C = 64.9 / 12 = 5.4

H = 13.5 / 1 = 13.5

O = 21.6 / 16 = 1.35

Divide by the smallest

C = 5.4 / 1.35 = 4

H = 13.5 / 1.35 = 10

O = 1.35 / 1.35 = 1

Thus, the empirical formula of the compound is C₄H₁₀O

How to determine the molecular formula of the compound

Molar mass of compound = 75.16 g/mol
Empirical formula = C₄H₁₀O
Molecular formula =?

Molecular formula = empirical × n = molar mass

[C₄H₁₀O]ₙ = 75.16

[(12×4) + (10×1) + 16]ₙ = 75.16

74n = 75.16

Divide both side by 74

n = 75.16 / 74

n = 1

Molecular formula = [C₄H₁₀O]ₙ

Molecular formula = [C₄H₁₀O]1

Molecular formula = C₄H₁₀O

Learn more about empirical and molecular formula:

https://brainly.com/question/24297883