- #1

Aya

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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

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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

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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

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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?

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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

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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

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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

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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

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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

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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

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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!