Question #08917

1 Answer
Feb 4, 2017

1
#0.3 * 1.204 * 10^24 = 3.612 * 10^23# H atoms
#0.7 * 1.204 * 10^24 = 8.428 * 10^23# atoms of unknown element

2
#3.612 * 10^23 # H atoms #* 1/(6.022 * 10^23)# mol/atoms #* 1.01/1# g/mol = 0.606g

So, #57.14 - 0.606# = 56.53g

3
#8.428 * 10^23 * 1/(6.022 * 10^23) = 1.3995# mol of unknown element

Molar mass = #56.53/1.3995 = 40.3# gmol

With slight error, this is the molar mass of argon on the periodic table (i.e 39.95 g/mol).