Question 1(multiple choice worth 3 points)
(06.04 mc)
a reaction produced 37.5 l of oxygen gas at 307 k and 1.25 atm. how many moles of oxygen were produced?
0.538 mol o2
1.86 mol o2
3.22 mol o2
7.56 mol o2
question 2(multiple choice worth 3 points)
(06.04 lc)
what is the volume of 1.5 moles of oxygen gas at standard temperature and pressure (stp)?
22 l
34 l
58 l
71 l
question 3(multiple choice worth 3 points)
(06.04 mc)
zinc metal and hydrochloric acid react together according to the following equation:
2hcl(aq) + zn(s) → zncl2(aq) + h2(g)
if 5.98 g zn reacts with excess hcl at 298 k and 0.978 atm, what volume of h2 can be collected?
2.29 l h2
3.32 l h2
4.58 l h2
7.41 l h2
question 4(multiple choice worth 3 points)
(06.04 mc)
read the given equation.
na2o2 + co2 → na2co3 + o2
what volume of o2 gas is produced from 2.80 liters of co2 at stp?
5.60 liters
4.20 liters
2.10 liters
1.40 liters
question 5(multiple choice worth 3 points)
(06.04 mc)
read the given equation.
2na + 2h2o → 2naoh + h2
during a laboratory experiment, a certain quantity of sodium metal reacted with water to produce sodium hydroxide and hydrogen gas. what was the initial quantity of sodium metal used if 8.40 liters of h2 gas were produced at stp?
17.2 grams
15.8 grams
12.3 grams
10.0 grams
question 6 (true/false worth 2 points)
(06.04 lc)
one mole of any gas at 298 k and 1 atm occupies a volume of 22.4 l.
true
false
question 7(multiple choice worth 3 points)
(06.04 lc)
at standard temperature and pressure, what is the volume of one mole of gas?
22.4 liters
0.0821 liters
the same as the molar mass of the gas
the product of protons, neutrons, and electrons in the gas

1)

moles of oxygen (n) = 1.86 moles

Explanation:

according to  Boyle's law the formula to solve this problem is:

PV=nRt

when P is the pressure which equal 1.25 atm

and V is the volume which equal 37.5 L

n is the number of moles which we need to calculate it

R is constant which equal 0.082

t is the temperature in kelvin

By substitution:

1.25*37.5 = n * 0.082 * 307

So n = 1.86 moles

2)

the volume of oxygen gas = 34 L

Explanation:

at standard temperature and pressure (STP) 1 mole of gas will equal = 22.4L

So when we have 1.5 moles of oxygen at standard temperature and pressure (STP) so we will estimate it like that

1.5 moles *22.4 L/ 1 mole = approximately 34 L

3)

The volume of H2 = 2.29 L

Explanation:

according to the Balanced equation we can see that the molar ratio between Zn and H2 1 : 1

so to know the number of moles of H2 we will get it for Zn first :

number of moles Zn = mass of Zn / molar mass Zn

                             = 5.98 / 65.39 =0.0914 moles

so number of moles H2 = 0.09 moles

by  substitution in the following formula:

PV = nRT

0.978 * V = 0.09 * 0.082 * 298

so The volume of H2 = 2.29 L

4)

Volume of O2 = 1.4 L

Explanation:

first we have to balance  the equation:

2Na2O2 +2CO2 → 2Na2CO3 + O2

2 mole CO2 give 1 mole of O2 so the molar ratio is 2:1

at STP 1 mole of gas will equal = 22.4 L

             ??? moles of CO2 = 2.8

n CO2 = 0.125 moles so n O2 = 0.125 /2 = 0.0625 moles

so when 1 mole of as = 22.4

              0.0625 moles O2 = ???

Volume of O2 =0.0625 moles * 22.4 L/ 1 mole

                        = 1.4 L

5)

the initial quantity of sodium metal used = 17.2 gram

Explanation:

at STP 1 mole of gas will equal = 22.4 L

so  moles of H2 equal ?? when 8.40 liters of H2 gas were produced

so moles of H2  = 8.4/22.4 =0.375 moles

and according to the balanced equation the molar ratio between H2 ans Na is 1 : 2

so number of moles for Na = 0.375 *2 = 0.75 moles

to get the initial quantity of sodium metal (mass Na) = number of moles * molar mass

mass Na = 0.75 moles * 23 gm/mole= 17.25

6)

False

Explanation:

because STP means standard temperature and pressure. and the Standard temperature must be 273 K and the standard pressure must be 1 atm but in the question the temperature is 298 K not 273 K so , It is not a standard temperature

7)

22.4 liters

Explanation:

1 mole of gas will equal = 22.4 L

because at the Standard temperature must be 273 K and the standard pressure must be 1 atm

so V = nRT/P

       =1 mole * 0.082 * 273 K / 1 aTm

        = 22.4 liters

these nuts

"standard molar enthalpy:

h2o ( liquid water ) : - 285.8 kj/mole

h2o ( water vapor ) : - 241.8 kj / mole.

δhrxn = - 241. 8 - ( - 285.8 )= -241.8 + 285.8 = 44.0

answer: 44.0 kj"