Question

< Question 4 of 9 > A 0.196 g sample of a metal, M, reacts completely with sulfuric acid according to M(s) + H2SO4 (aq) → MSO4 (aq) + H2(g) A volume of 205 mL of hydrogen is collected over water; the water level in the collecting vessel is the same as the outside level. Atmospheric pressure is 756.0 Torr, and the temperature is 25 °C. Calculate the molar mass of the metal. molar mass: g/mol

Answer 1

To find the molarmass of the metal Given that 0.196 g sample of metal M(s)+H,80, (aq) →M50(aq) +H2() First find the moles hydrogen gas Use theideal gas law PV = nRT p = pressure n=n moles of any gas R = gas constant T = temperature in kelvin v=volume p= 756. Otorr Convert pressure torr to atm 1 atm = 760 torr 1 atm 756.0torr = 756. Otorr - = 0.994 atm 760torr n = ? R = 0.0821L atm/mol. K T = 25+273K = 298K V = 205mL = 0.205L PV 0.994atm x 0.205L " 0.0821L atm/ mol-Kx298K n = 0.00832 moles find the moles of the metal According to reaction metal and hydrogen is 1:1 mole ratio Therefore moles of the metal = 0.00832 moles To find the molarmass of the metal molarmass = mass moles 0.196 g 0.00832moles = 23.55g/mol Hence the molarmass of the metal = 23.55 g/mol