Name, Answer all questions. Answers containing incorrect units will have minus o
ID: 304571 • Letter: N
Question
Name, Answer all questions. Answers containing incorrect units will have minus o.5 points. Points per question are noted. barometric pressure is 777 torr. What is the pressure of (2) A gas is collected over water at 25°c when the the gas in atm? The pressure of water at 25°C is 23.78 mm Hg 1. (5) The following reaction is used to generate hydrogen gas in the laboratory. If 243 ml over water at 20'C and has a total pressure of 745 mm Hg, what mass (s) of hydrogen of gas is collected is produced? 2. ICC) 20 25 30 P (mm Hg) 17.55 23.78 31.86 Znís)+HClag)Zncl2fag)H2(8) 3. (3) What volume of hydrogen gas can be produced by the reaction of 1.268 g of Mg at STP? Mgls) + HCl(aq) Mgcl2(aq) +H2(8)Explanation / Answer
1.The baromatric pressure = 777torr
The pressure of water = 23.78torr
The pressure of gas = .The baromatric pressure - The pressure of water
= 777-23.78 = 753.22 torr
= 753.22/760 = 0.99atm
The pressure of gas = 0.99atm
2. The total pressure = 745mmHg
The vapor pressure of water = 17.55mmHg
The pressure of H2 gas = 745-17.55 = 727.45 mmHg
P = 727.45/760 = 0.957atm
V = 243ml = 0.243L
T = 20+273 = 293K
PV = nRT
n = PV/RT
= 0.957*0.243/0.0821*293 = 0.00967moles
mass of H2 = no of moles * gram molar mass
= 0.00967*2 = 0.01934g
3. Mg(s) + 2HCl(aq) -----------> MgCl2(aq) + H2(g)
1 mole of Mg react with HCl to gives 1 mole of H2
24g of Mg react with HCl to gives 22.4L of H2
1.268g of Mg react with HCl to gives = 22.4*1.268/24 = 1.1835L of H2
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