I need help with these Chemistry quoestions?

[匿名]

2016-05-10 6:01 am

1. Calculate the volume that a 0.323 mol sample of a gas will occupy a 265 K and a pressure of 0.900 atm

2. How many grams of mass are present in a sample that has a molar mass of 70.0 g/mol and occupies a 3.00 L container at 119 kPa and 35.6 C?

3. Ammonium nitrate is a common ingredient in chemical fertilizers. Use the reaction shown to calculate the mass of solid ammonium nitrate that must be used to obtain 0.300 L of dinitrogen oxide at STP.
NH4NO3 ---> N2O(g) + 2 H2O (g)

4. Determine how many moles of water vapor will be produced at 2.00 atm and 250 C by the complete combustion of 10.5L of methane gas (CH4).
CH4(g) + 2O2(go) ---> CO2(g) + 2H2O (g)

5. Solid potassium metal will react with Cl2 gas to form ionic potassium chloride. How many liters of Cl2 gas are neede to completely react with 0.204 g of potassium at STP?

回答 (1)

fooks

2016-05-10 8:21 am

1.
PV = nRT
Volume, V = nRT/P = 0.323 × 0.0821 × 265 / 0.900 L = 7.81 L

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2.
PV = nRT
n = PV/(RT) = 119 × 3.00 / [8.314 × (273.2 + 35.6)] = 0.139 mol

Mass = (70.0 g/.mol) × (0.139 mol) = 9.73 g

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3.
Mole ratio NH₄NO₃ : N₂O = 1 : 1
No. of moles of N₂O = (0.3 L) / (22.4 L/mol) = 0.01339 mol
No. of moles of NH₄NO₃ = 0.01339 mol

Molar mass of NH₄NO₃ = 14.01×2 + 1.01×4 + 16.00×3 = 80.06 g/mol
Mass of NH₄NO₃ = (80.06 g/mol) × (0.01339 mol) = 1.07 g

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4.
T = (273 + 250) K = 523 K
PV = nRT
n = PV/(RT)
No. of moles of CH₄, n = 2.00 × 10.5 / (0.0821 × 523) mol = 0.489 mol

According to the given equation, mole ratio CH₄ : H₂O = 1 : 2
No. of moles of H₂O vapor formed = (0.489 mol) × 2 = 0.978 mol

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5.
Molar mass of K = 39.01 g/mol
No. of moles of K used = (0.204 g) / (39.01 g/mol) = 0.005229 mol

2K + Cl₂ → 2KCl
mole ratio K : Cl₂ = 2 : 1
No. of Cl₂ used = (0.005229 mol) × (1/2) = 0.002615 mol

1 mol of Cl₂ occupies 22.4 L at STP.
Volume of Cl₂ at STP = (22.4 L/mol) × (0.002615 mol) = 0.0586 L

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