Quiz 5 October 21, 2014

Transcription

1 Chem 1711 Name Quiz 5 October 21, 2014 PV = nrt PM = drt R = L atm K 1 mol 1 1. A sample of gas at some volume and temperature exerts a pressure of atm. Determine what will happen when each of the following changes is made independently to this system with this starting P, V, and T. a. If, at constant volume, an additional mol gas is added and the temperature is increased, will the pressure exerted increase, decrease, or remain constant? b. If the volume occupied by this sample of gas is increased at constant temperature, will the pressure exerted increase, decrease, or remain constant? c. If 1.50 mol of a different gas is added to the container at constant V and T, will the total pressure exerted by the system be less than, greater than, or equal to atm? 2. Consider a mixture of He (g) and Ar (g) that exerts a total pressure of 4.50 atm in a 2.50 L vessel at 315 K. In this mixture the mole fraction of helium is a Determine the total amount (in mol) of gas in this mixture. n tot = mol b. Determine the amount (in mol) of helium in this mixture. n He = mol c. Determine the partial pressure (in atm) exerted by the argon in this mixture. P Ar = atm 3. a. True or False? For a sample of an ideal gas at constant T, a plot of P V vs. V will be a curve. b. At STP, the volume occupied by mol of an ideal gas is L. c. A pressure of 1624 mmhg is equal to torr. d. True or False? For a given sample of gas at constant P, density will decrease as temperature increases. e. Consider a mixture of two nonreactive gases X (g) and Z (g) at a constant volume and temperature. The partial pressure of X (g) is 791 torr, and the partial pressure of Z (g) is 158 torr. For this mixture, P tot = torr, and χ Z =.

2 4. a. Calculate the volume (in L) occupied by g Xe (g) at 495 K and 6.94 atm. L b. Determine the molar mass of a gas with a density of g/l at atm and 72 C. g/mol c. Determine the molar volume (in L/mol) of a gas at 525 mmhg and 194 K. L/mol d. A mol sample of Ne (g) exerts a pressure of atm at some T and V. If additional Ne (g) is added (at the same T and V), and the pressure exerted increases to atm, determine the number of additional mol gas added. mol 5. Consider the combustion of hexane: 2 C 6 H 14 (g) + 19 O 2 (g) 12 CO 2 (g) + 14 H 2 O (g). 275 g of O 2 (g) is allowed to react with excess hexane, and the reaction goes to completion. Determine the pressure (in atm) exerted in a L vessel at 20 C by the CO 2 (g) produced. atm

3 Bonus Questions (worth a possible maximum of 4 points added to your Quiz 4 score): 1. Pyridine (C 5 H 5 N) is a weak base. Complete the equation below to show how pyridine ionizes in water: C 5 H 5 N (aq) + H 2 O (l) (aq) + (aq) 2. Write the net ionic equation for the neutralization reaction between nitrous acid and potassium hydroxide: 3. A sample of Na (s) is combined with H 2 O (l). Circle all of the statements below that are true. O undergoes a 2 e reduction Na is the reducing agent H is reduced O 2 is the oxidizing agent Na undergoes a 2 e oxidation in the balanced equation 1 mol H 2 (g) is formed no reaction will occur 4. Circle the letter of the one reaction below that will not occur as written. a. Ni (s) + 2 HCl (aq) NiCl 2 (aq) + H 2 (g) d. HIO 3 (aq) + NH 3 (aq) NH 4 IO 3 (aq) b. Ni (s) + MgCl 2 (aq) Mg (s) + NiCl 2 (aq) e. Br 2 (l) + 2 KI (aq) 2 KBr (aq) + I 2 (s) c. 2 HNO 3 (aq) + CaCO 3 (s) Ca(NO 3 ) 2 (aq) + H 2 O (l) + CO 2 (g) f. all of these will occur as written

4 Chem 1711 Name Quiz 5 October 21, 2014 PV = nrt PM = drt R = L atm K 1 mol 1 1. a. True or False? For a given sample of gas at constant P, density will decrease as temperature increases. b. A pressure of 1760 torr is equal to mmhg. c. True or False? For a sample of an ideal gas at constant T, a plot of P V vs. V will be a curve. d. At STP, the volume occupied by mol of an ideal gas is L. e. Consider a mixture of two nonreactive gases X (g) and Z (g) at a constant volume and temperature. The partial pressure of X (g) is 841 torr, and the partial pressure of Z (g) is 325 torr. For this mixture, P tot = torr, and χ Z =. 2. Consider a mixture of He (g) and Ar (g) that exerts a total pressure of 5.75 atm in a 3.00 L vessel at 333 K. In this mixture the mole fraction of helium is a Determine the total amount (in mol) of gas in this mixture. n tot = mol b. Determine the amount (in mol) of helium in this mixture. n He = mol c. Determine the partial pressure (in atm) exerted by the argon in this mixture. P Ar = atm 3. A sample of gas at some volume and temperature exerts a pressure of atm. Determine what will happen when each of the following changes is made independently to this system with this starting P, V, and T. a. If the volume occupied by this sample of gas is increased at constant temperature, will the pressure exerted increase, decrease, or remain constant? b. If, at constant volume, an additional mol gas is added and the temperature is increased, will the pressure exerted increase, decrease, or remain constant? c. If 1.50 mol of a different gas is added to the container at constant V and T, will the total pressure exerted by the system be less than, greater than, or equal to atm?

5 4. a. Calculate the volume (in L) occupied by g Xe (g) at 495 K and 6.94 atm. L b. A mol sample of Ne (g) exerts a pressure of atm at some T and V. If additional Ne (g) is added (at the same T and V), and the pressure exerted increases to atm, determine the number of additional mol gas added. mol c. Determine the molar mass of a gas with a density of g/l at atm and 92 C. g/mol d. Determine the molar volume (in L/mol) of a gas at 625 mmhg and 414 K. L/mol 5. Consider the combustion of hexane: 2 C 6 H 14 (g) + 19 O 2 (g) 12 CO 2 (g) + 14 H 2 O (g). 275 g of C 6 H 14 (molar mass = g/mol) is allowed to react with excess O 2, and the reaction goes to completion. Determine the pressure (in atm) exerted in a L vessel at 20 C by the CO 2 (g) produced. atm

6 Bonus Questions (worth a possible maximum of 4 points added to your Quiz 4 score): 1. Pyridine (C 5 H 5 N) is a weak base. Complete the equation below to show how pyridine ionizes in water: C 5 H 5 N (aq) + H 2 O (l) (aq) + (aq) 2. Write the net ionic equation for the neutralization reaction between nitrous acid and potassium hydroxide: 3. A sample of Na (s) is combined with H 2 O (l). Circle all of the statements below that are true. Na undergoes a 2 e oxidation in the balanced equation 1 mol H 2 (g) is formed O 2 is the oxidizing agent O undergoes a 2 e reduction Na is the reducing agent H is reduced no reaction will occur 4. Circle the letter of the one reaction below that will not occur as written. a. HIO 3 (aq) + NH 3 (aq) NH 4 IO 3 (aq) d. Ni (s) + MgCl 2 (aq) Mg (s) + NiCl 2 (aq) b. Br 2 (l) + 2 KI (aq) 2 KBr (aq) + I 2 (s) e. Ni (s) + 2 HCl (aq) NiCl 2 (aq) + H 2 (g) c. 2 HNO 3 (aq) + CaCO 3 (s) Ca(NO 3 ) 2 (aq) + H 2 O (l) + CO 2 (g) f. all of these will occur as written