18.8 grams of gas occupies 14.5 L at 79.9 kPa at 30.0 Celsius degree. What is It’s molecular weight?(grams /moles)

Answer : The molecular weight of gas is, 40.9 g/mol

Explanation :

To calculate the molecular weight of gas we are using ideal gas equation:

where,

P = pressure of gas = 79.9 kPa

V = volume of gas = 14.5 L

T = temperature of gas =

R = gas constant = 8.314 L.kPa/mole.K

w = mass of gas = 18.8 g

M = molecular weight of gas = ?

Now put all the given values in the ideal gas equation, we get:

Therefore, the molecular weight of gas is, 40.9 g/mol

given:

mass of na = 115 g

excess cl2

to determine:

mass of nacl produced

explanation:

given reaction is-

2na(s) + cl2(g) → 2nacl(s)

since cl2 is in excess, na will be the limiting reagent

as per the reaction stoichiometry na: nacl = 1: 1

i.e. moles of na reacted = moles of nacl formed

now, # moles of na = mass of na/atomic mass

                                  = 115 g/23 g.mol-1 = 5 moles

therefore, moles of nacl = 5

molar mass of nacl = 58 g/mol

mass of nacl = 5 moles * 58 g.mol-1 = 290 g

ans: amount of nacl produced = 290 g