An experiment is performed in which the molar mass of a gas is found to be 48.45 gmol-1. the published (actual) value is 52.98 g mol. calculate the percentage error.

Experimental molar mass = 48.45 g/mol. Actual molar mass = 52.98 g/mol. Error in molar mass= (52.98-48.45) = 4.53. Percentage error in molar mass= (Error in molar mass)/Actual molar mass = (4.53/52.98)X100= 8.55 %. The formula utilised here is percentage error= (Exact value - Approximate value)X100/Exact value. First approximate value is to be subtracted  from exact value, then divide the number by exact value. Finally, the fraction is to be multiplied by 100 to get percentage error.