An experiment shows that a 111 ml gas sample has a mass of 0.168 g at a pressure of 734 mmhg and a temperature of 34 ∘c. what is the molar mass of the gas?

hey there!:

Volume in liters ( V ) = 111 mL / 1000 => 0.111 L

Pressure in atm ( P )  = 734 / 760 => 0.965789 atm

temperature in Kelvin ( K )  = 34+273.15 => 307.15 K

Molar gas constant ( R ) = 0.0826 atm*L/mol*K

ideal gas  equation :

p*V = n*R*T

moles of gas:

n =  p*v / R*T

n = 0.965789 * 0.111 / 0.0826 * 307.15

n = 0.107202 / 25.37059

n = 0.004225 moles

Therefore:

Molar mass =  mass / moles of gas

molar mass = 0.168 / 0.004225

molar mass = 39.76 g/mol

Hope this helps!

i believe you are right for all except the 3rd ( look at sqdancefan his answer is much better)

the enthalpy of formation of water is given as -285.8kj/mol, which states that the enthalpy of formation is negative.

negative enthalpy of formation indicates that the heat is released during the reaction process. the heat is released from reaction to the surroundings the enthalpy is expressed with a negative sign with the energy given out in the reaction process.

the formation of water takes place by giving out heat which is -285.8 kj/mol.