Name: R = 0.0821 Latm
PV = nRT
P1 V1\ n1 T1 =P2 V2/ n2 T2
1. What volume, will be occupied by 3.86 g of C2H2 gas (acetylene) at 2.50 atm and a temperature
of 28.5 °C?
2. A gas at 650.0 torr and 75 °C is cooled to 25 °C. What is the pressure of the gas after it has
cooled?

1. V = 1.47L

Explanation:

1) Using PV = nRT

Where;

P = pressure (atm)

V = volume (L)

R = gas constant (0.0821 Latmk mol)

n = number of moles

T = temperature (K)

To get number of moles, we say mole = mass/molar mass

Molar Mass of C2H2 = 12(2) + 1(2)

= 24 + 2 = 26g/mol

mole = 3.86/26

mole = 0.148mol

T (K) = 28.5°C + 273.15

T(K) = 301.65K

PV = nRT

2.5 × V = 0.148 × 0.0821 × 301.65

2.5V = 3.665

V = 3.665/2.5

V = 1.466

V = 1.47L

R =

PV = nRT

P1 V1\ n1 T1 =P2 V2/ n2 T2

1. What volume, will be occupied by 3.86 g of C2H2 gas (acetylene) at 2.50 atm and a temperature

of 28.5 °C?

2. A gas at 650.0 torr and 75 °C is cooled to 25 °C. What is the pressure of the gas after it has

cooled?

"standard molar enthalpy:

h2o ( liquid water ) : - 285.8 kj/mole

h2o ( water vapor ) : - 241.8 kj / mole.

δhrxn = - 241. 8 - ( - 285.8 )= -241.8 + 285.8 = 44.0

answer: 44.0 kj"