45) using ideal gas equation , PV= nRT V=25L , P=702mmHg = 702/760 atm, T=22.5 o

Question

45) using ideal gas equation , PV= nRT

V=25L , P=702mmHg = 702/760 atm, T=22.5oC = 295.5K

R, gas constant =0.0821Latm/mol/K

n =( 702 *25)/ (760*0.0821*295.5) = 0.95mol

46) According to stoichiometry of given reaction,

149g of KCl is obtained by 111 g CaCl2

So 10g KCl is obtained by 111*10/149 = 7.44g of CaCl2

47) P=780/760atm, T=135+273 = 408K, V=0.5L

n= PV/RT = (780*0.5)/(760*408*0.082) = 0.015mol

No.of molecules= no.of moles* 6.022*1023

=0.015*6.022 *1023 = 9.23 * 1021

48) P1 T2 = P2 T1

1* (475+273) =P2 * 298

P2 = 2.51atm

49) Accor. To stoichiometry of reaction,

1mol N2. Requires 3mol H2

so 6mol N2 requires 18mol H2

but we have only 6mol H2 so H2 is limiting reagent.

3mol H2 forms 2mol NH3

So 6 mol H2 forms 4mol NH3.

vol. Of 1mol NH3 at STP = 22.4L

SO VOL. of 4mol NH3 = 22.4* 4 = 89.6L

50) hydrogen has highest first ionization enthalpy as its e- is present in first shell feels high nuclear charge thus large amount of energy is required to remove it.

Explanation / Answer

45) A gas evolved during the fermentation of sugar was collected. After purification its volume was found to be 25.0 L at 22.5°C and 702 mmHg. How many moles of gas were collected? A. 0.95 mol B. 1.05 mol C. 12.5 mol D. 22.4 mol E. 724 mol 46) How many grams of calcium chloride are needed to produce 10.0 g of potassium chloride? CaCl2(aq) + K2CO3(aq) 2 KCI(aq) + CaCO3(aq) A) 0.134 g B) 7.44 g C) 14.9 g D) 29.8 g 47) How many molecules of N2 are in a 500.0 mL container at 780 mm Hg and 135 'C? A) 8.76 x 1021 B) 9.23 x 1021 C)2.65 1022 D) 2.79 x 1022 48) An "empty" aerosol can at 25°C still contains gas at 1.00 atmosphere pressure. If an "empty" can is thrown into a 475°C fire, what is the final pressure in the heated can? A) 5.26 x 10-2 atm B) 0.398 atm C) 2.51 atnm D) 19.0 atm 49) At STP how many liters of NH3 can be produced from the reaction of 6.00 mol of N2 with 6.00 mol of H2? N2(g) + 3 H2(g) 2 NH3(g) A) 44.8 L B) 89.6 L C) 134 L D) 269 L 50) Of the following, which element has the highest first ionization energy? A) beryllium C) hydrogen D) lithium

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