- #1
Aya
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Hi, I have some reviw questions for the upcomming chemistry exam, the problem is I don't have the answers so can some one read throught my work and check if it is wright? Thanks.
***
1. An anaysis of a valitile liquid showed that it wsa composed of 14.4%C, 2.37% H and 83.49% Cl. If 4.25 g of the liquid was vaporized and occupied 628 mL at 65 degrees celcuios and 112 kpa, what would be the molecular formula of the compund?
carbon
14.4% x 100g
= 14.4 g
m=14.4 g
n=1.199 mol
Mm=12.01 g/mol
hydrogen
2.37% x 100g
=2.37g
m=2.37 g
n=2.347mol
Mm=1.01 g/mol
Cholrine
83.49% x 100g
=83.49g
m=83.49 g
n=2.355mol
Mm=35.45 g/mol
so...
1.199 / 1.199 =1
2.37 / 1.1.99=2
2.355/ 1.199=2
Impirical Formula
C1 H2 Cl2
# mol of Impirical formula
PV=nrt
n=PV/rt
n=(112Kpa)(0.628L)/ 8.314kpaL/molL (388k)
n=0.025 mol
Molar mass of Impreical formula
Mm=m/n
Mm=4.25g/0.025 mol
Mm=170 g/mol
Molar mass of ( what is this the molar mass of?)
C1 H2 Cl2
84.93
Find a Factor
170g/mol/ 84.93 g/mol
=2
Molecular Formula
2(C1 H2 Cl2)
C2 H4 Cl4
***
2. A gas has a volume of 40.0 ml at 40 degrees celcuios and 95 Kpa. What will be its volume at STP?
gas
40.0 mL = 0.04L
40 degrees celcioue=313 K
95 kPa=P
n=rt/pv
n= 8.134(313)/95(0.04)
n=27.3890 mol
v=nrt
v=27.3809(8.134)(273)/101.3
v=613.4948
***
3. How many grams of sodium and required to product 2.24 L of Hydrogen gas, measured at 25 degrees celcuoiu adn 110 Kpa, according to the following reaction?
2Na + 2 H2O ---> 2 NaOH + H2O
n=rt/pv
n= 8.314(298)/110(2.24)
n=10.055
m=nMm
m=20.11 (22.99)
m=462.3289
B)calculate the volume of H2(g) produced when 54 g of Na(s) reacts with an excess of water at STP.
moles of Na
n=m/Mm
n=54/22.99
n=2.348
moles H
3.348/2
1.174
Volume
v=nrt/p
1.174(8.314)(273)/101.3
v=2.791
***
4. An aquois solution has a volume of 2.0L and contains 36.0 g of glucose. If the molar mass of glucose is 180 g , what is the molarity of the solution?
molar mass of glucose
n=m/Mm
n=36.0/180
n=0.2
...what next?
***
5. How would you prepare 100ml of 0.40 mol/L MgSO4 form a stock solution of 2.0 mol/L MgSO4?
n=0.100L/0.40 mol/L
0.25
v=n/c
v=0.25/2.0
v=0.125L
add 0.125L of MgSO4
***
6. A solution contains 5.85 g of sodium chlride dissolved in 5.00 x 10^3 ml of water. What is the concentration of the sodium cholirde solution?
n=M/Mm
n=0.0568 mol
C=n/v
0.0568/5
=0.01136 mol/L
***
7.what mass of potassium hydroxide is required to prepare 6.00 x 10^2 ml of a solution with a concentration of 0.225 mol/L
m=cv
0.225(0.5)
0.135mol
***
8. What volume of 0.500mol/L sodium hyroxide solution can be prepared form 10.0 ml of a 6.00 mol/L solution?
C1V1=C2V2
6(0.01)=0.500(v2)
0.12=v2
***
9. What is the mass of hydrochoric acid that is present in 500 mL of a solution containg 3.50 mol/L of HCl(aq)?
n=cv
3.50(0.5)
=1.75 mol
m=nMm
1.75(36.46)
63.805g
***
10. Passing a park throught a mixture of hydrogen gas and oxygen gas produced water
a) calculate the mas of hydrogen needed to completely convert 4.00 g of oxygen into water
H2 + O = H2O
moles of O
n=m/Mm
4.00/18.025
0.22
moles of H
0.22 mol
mass of H
m=nMm
=0.22(1.01)
=0.224
b) calcute the number of moles of oxygen required to react with 12.5 moles of hydrogen gas
I don't know how to do this one
c)calculate the number of moles of water produced when 4.00 g of oxygen are used
I don't know how to do this one
***
Thanks for reading pleas post any corrections and solutions to the problems I don't know how to do. this is practise for an exam so pleas help!
***
1. An anaysis of a valitile liquid showed that it wsa composed of 14.4%C, 2.37% H and 83.49% Cl. If 4.25 g of the liquid was vaporized and occupied 628 mL at 65 degrees celcuios and 112 kpa, what would be the molecular formula of the compund?
carbon
14.4% x 100g
= 14.4 g
m=14.4 g
n=1.199 mol
Mm=12.01 g/mol
hydrogen
2.37% x 100g
=2.37g
m=2.37 g
n=2.347mol
Mm=1.01 g/mol
Cholrine
83.49% x 100g
=83.49g
m=83.49 g
n=2.355mol
Mm=35.45 g/mol
so...
1.199 / 1.199 =1
2.37 / 1.1.99=2
2.355/ 1.199=2
Impirical Formula
C1 H2 Cl2
# mol of Impirical formula
PV=nrt
n=PV/rt
n=(112Kpa)(0.628L)/ 8.314kpaL/molL (388k)
n=0.025 mol
Molar mass of Impreical formula
Mm=m/n
Mm=4.25g/0.025 mol
Mm=170 g/mol
Molar mass of ( what is this the molar mass of?)
C1 H2 Cl2
84.93
Find a Factor
170g/mol/ 84.93 g/mol
=2
Molecular Formula
2(C1 H2 Cl2)
C2 H4 Cl4
***
2. A gas has a volume of 40.0 ml at 40 degrees celcuios and 95 Kpa. What will be its volume at STP?
gas
40.0 mL = 0.04L
40 degrees celcioue=313 K
95 kPa=P
n=rt/pv
n= 8.134(313)/95(0.04)
n=27.3890 mol
v=nrt
v=27.3809(8.134)(273)/101.3
v=613.4948
***
3. How many grams of sodium and required to product 2.24 L of Hydrogen gas, measured at 25 degrees celcuoiu adn 110 Kpa, according to the following reaction?
2Na + 2 H2O ---> 2 NaOH + H2O
n=rt/pv
n= 8.314(298)/110(2.24)
n=10.055
m=nMm
m=20.11 (22.99)
m=462.3289
B)calculate the volume of H2(g) produced when 54 g of Na(s) reacts with an excess of water at STP.
moles of Na
n=m/Mm
n=54/22.99
n=2.348
moles H
3.348/2
1.174
Volume
v=nrt/p
1.174(8.314)(273)/101.3
v=2.791
***
4. An aquois solution has a volume of 2.0L and contains 36.0 g of glucose. If the molar mass of glucose is 180 g , what is the molarity of the solution?
molar mass of glucose
n=m/Mm
n=36.0/180
n=0.2
...what next?
***
5. How would you prepare 100ml of 0.40 mol/L MgSO4 form a stock solution of 2.0 mol/L MgSO4?
n=0.100L/0.40 mol/L
0.25
v=n/c
v=0.25/2.0
v=0.125L
add 0.125L of MgSO4
***
6. A solution contains 5.85 g of sodium chlride dissolved in 5.00 x 10^3 ml of water. What is the concentration of the sodium cholirde solution?
n=M/Mm
n=0.0568 mol
C=n/v
0.0568/5
=0.01136 mol/L
***
7.what mass of potassium hydroxide is required to prepare 6.00 x 10^2 ml of a solution with a concentration of 0.225 mol/L
m=cv
0.225(0.5)
0.135mol
***
8. What volume of 0.500mol/L sodium hyroxide solution can be prepared form 10.0 ml of a 6.00 mol/L solution?
C1V1=C2V2
6(0.01)=0.500(v2)
0.12=v2
***
9. What is the mass of hydrochoric acid that is present in 500 mL of a solution containg 3.50 mol/L of HCl(aq)?
n=cv
3.50(0.5)
=1.75 mol
m=nMm
1.75(36.46)
63.805g
***
10. Passing a park throught a mixture of hydrogen gas and oxygen gas produced water
a) calculate the mas of hydrogen needed to completely convert 4.00 g of oxygen into water
H2 + O = H2O
moles of O
n=m/Mm
4.00/18.025
0.22
moles of H
0.22 mol
mass of H
m=nMm
=0.22(1.01)
=0.224
b) calcute the number of moles of oxygen required to react with 12.5 moles of hydrogen gas
I don't know how to do this one
c)calculate the number of moles of water produced when 4.00 g of oxygen are used
I don't know how to do this one
***
Thanks for reading pleas post any corrections and solutions to the problems I don't know how to do. this is practise for an exam so pleas help!