How many molecules of n2 are in a 400.0 ml container at 780 mm hg and 135°c? avogadro’s number = 6.022 x 1023a) 7.01 × 1021 moleculesb) 7.38 × 1021 moleculesc) 2.12 × 1022 moleculesd) 2.23 × 1022 molecules

B

Explanation:

Firstly, we will need to calculate the number of moles. To do this, we make use of the ideal gas equation

PV = nRT

n = PV/RT

The parameters have the following values according to the question:

P = 780mmHg, we convert this to pascal.

760mHG = 101325pa

780mmHg = xpa

x = (780 * 101325)/760 = 103,991 Pa

V= 400ml = 0.4L

T = 135C = 135 + 273.15 = 408.15K

n = ?

R = 8314.463LPa/K.mol

Substituting these values into the equation yields the following:

n = (103991 * 0.4)/(8314.463 * 408.15)

= 0.012 moles

Now we know 1 mole contains 6.02 * 10^23 molecules, hence, 0.012moles will contain = 0.012 * 6.02 * 10^23 = 7.38 * 10^21 molecules