IDEAL GAS LAW QUESTIONS PLEASE HELP!!?

Question

1) A copper ball with a radius of 1.5cm is heated until its diameter has increased by 0.19 mm.

A) Assuming an initial temperature of 23 degree Celcius, find the final temperature of the ball.

2) A 550 cm^3 flask contains 0.440g of a gas at a pressure of 140 kPa and a temperature of 325K .

A) What is the molecular mass of this gas?

Answer 1

1)

Initial radius,r1=1.5 cm

Initial diameter ,d1=3 cm

Final diameter,d2=3+(0.19/100)

                                =3.0019 cm

Initial temperature,T1=23 degree Celcius

                                       =296 K

Initial volume,V1=(4/3)pi*r1^3

                              =(4/3)*pi*1.5^3

                              =14.137 cm^3

Initial volume,V2=(4/3)pi*r2^3

                              =(4/3)*pi*(3.0019/2)^3

                              =14.164 cm^3

V1/T1=V2/T2

T2=V2T1/V1

     =14.164*296/14.137

     =296.565K

     =23.565 degree Celcius

-----------------------------------------------------

2)

Volume,V=550 cm^3=550*10^-4 m^3

Mass,m=0.44 g=0.44*10^-3 kg

Pressure,P=140 kPa=140*10^3 Pa

Temperature,T=325 K

PV=(m/M)RT

M=(m/PV)RT

    =(0.44*10^-3/140*10^3*550*10^-4)*8.3145*325

    =11.89 moles