Molarity, Dilutions, & Gas Laws

​This Test is ALL math

This Quizizz lesson will focus on how to do that math

Write down examples of ones you do not understand in your notes!!!!!!!

Copyright © 2011 MsRazz ChemClass

Solutions and

Molarity

Introduction to Solutions

Copyright © 2011 MsRazz ChemClass

Moles
(mol)

Molarity

(M)

Liters of
solution

(L)

​This is the equation you need to know for molarity!

Copyright © 2011 MsRazz ChemClass

Ex 1 Calculations

With Molarity

Example: What is the molarity of a solution that
contains 0.25 moles of NaCl in 0.75L of solution?
M=
mol=
L=

?

0.25 mol NaCl

0.75L

M = 0.25 mol NaCl

0.75L

Molarity = 0.33 mol/L or 0.33M

Copyright © 2011 MsRazz ChemClass

Example 2 Calculations

With Molarity

Example: What volume of a 1.08M KI solution
would contain 0.642 moles of KI?
M=
mol=
L=

1.08 M

0.642 mol KI

?

Volume= 0.594L

​L= mol 

MMolarity

​0.642mol 

M1.08 M

Copyright © 2011 MsRazz ChemClass

Performing Calculations

With Molarity

Example: How many grams of CaBr2 are dissolved
in 0.455L of a 0.39M CaBr2 solution?
M=
mol=
L=

0.39 M CaBr2

?

0.455L

0.39 M =

0.455L X

mol = 0.18 mol CaBr2

0.18 mol CaBr2 x 1 mol CaBr2

199.88gCaBr2 = 36g CaBr2

1 Ca=40.08
2 Br=79.90(2)

199.88g

​Molar Mass Calculation

​Reminder:

If a Question

mentions grams

MOLAR MASS

will be used

Molarity: Extra Practice

​These videos will walk through extra problems

You do not have to watch it all

Watch what YOU NEED. This is YOUR Review

​Links.....

https://www.youtube.com/watch?v=yb4FW6E1HKE

Multiple Choice

How many grams of FeCl ₃ are needed to make 0.60 L of a 3.6 M solution?

• 55.60 g

• 0.013 g

• 0.13g

• 13.0 g

Multiple Choice

What is the molarity of 0.235 L solution containing 0.48 moles of solute?

• 5.0 M

• 0.113 M

• 0.49 M

• 2.04 M

Dilutions

Dilution Example

To determine the new molarity, we have to know an equation

The equation for dilution is

M1V1=M2V2

M1= molarity of the stock solution
M2= molarity of the diluted solution

V1= volume of stock solution
V2= volume of diluted solution

1 is before dilution
2 is after dilution

Dilution Example

​Values next to each other, stay together

​Work this question out, be ready to answer it on the next slide

Multiple Choice

What is the was the volume?

• 31.5 ml

• 40 ml

• 3.15 ml

Gas Laws

​REMINDER

You ONLY change units, when they DO NO MATCH

Units of Pressure

● At Standard Atmosphere Pressure

1 atm (atmosphere)

○ 101.33 kPa

(kilopascal)

○ 760 mm Hg

(millimeter Hg)

●

=

*

Different units used for

pressure

​This on the back of your periodic table

Temperature: The Kelvin Scale

K = ºC + 273

● ALWAYS use absolute temperature

(Kelvin) when working with gases.

*

​This on the back of your periodic table

Boyle’s Law

Volume ∝ 1 ⁄ pressure

● If the volume increases = pressure

decrease

● If volume decreases= pressure will increase

moles (n) & temperature remain constant

1. Boyle’s Law

Boyle’s Law leads to the mathematical
expression: *Assuming temp is constant

P1V1=P2V2

​Work this question out, be ready to answer it on the next slide

Both pressure units MATCH, so no conversion is needed

Multiple Choice

What is the volume?

• 300 L

• 195 L

• 195,000 mL

Boyle's : Extra Practice

​Link

https://www.youtube.com/watch?v=uBIx0h6P4vM

2. Charles’ Law

2. Intro to Charles’ Law

Hot air balloons

Hot air makes temperature go

inflating the balloon aka volume

Example Problem:

A gas has a volume of 4.0L at 27°C. What is
its volume at 153°C?
V1=
T1=
V2=
T2=

​Work this question out, be ready to answer it on the next slide

​REMINDER- Temperature needs to be converted to Kelvin

​Use the butterfly method

Multiple Choice

A gas has a volume of 4.0L at 27°C. What is its volume at 153°C?

• 4.9 L

• 5.65 L

• 5.6 L

• 7.5 L

Charles' : Extra Practice

​Link

https://www.youtube.com/watch?v=A9MXM60vBKM

3. Intro to Gay-Lussac's Law

● Tire is filled with a gas,

oxygen.

● It has a fixed volume
● What happens to tire

pressure when the
temperature is cold outside?

Pressure ∝ Temperature

● If the volume

decreases/increases =

temperature will

decreases/increase

Example Problem:

A gas has a pressure of 103kPa at 25°C. What will
the pressure be when the temperature reaches
928°C?
P1=
T1=
P2=
T2=

​Work this question out, be ready to answer it on the next slide

​Use the butterfly method

Multiple Choice

A gas has a pressure of 103kPa at 25°C. What will the pressure be when the temperature reaches 928°C?

• 60 kPa

• 145 kPa

• 415 kPa

Gay-Lussac's : Extra Practice

​Link

https://www.youtube.com/watch?v=i45L1e_Cw6M

4. Combined Gas Law

P1V1

T1

=

P2V2

T2

This is on the back of the periodic table. Cover up what you are not given and then you have the equation you need.

4. Avogadro’s Law

5. Avogadro’s Law

Volume and the amount of gas (moles) are

directly proportional
Volume ∝ moles

V1 V2
n1 n2

=

​

​

​V1

​V2

​n1

​n2

​Use the butterfly method

Example Problem:

5.00 L of a gas is known to contain 0.965 mol. If
the amount of gas is increased to 1.80 mol, what
new volume will result
V1=
n1=
V2=
n2=

​Work this question out, be ready to answer it on the next slide

Multiple Choice

5.00 L of a gas is known to contain 0.965 mol. If the amount of gas is increased to 1.80 mol, what new volume will result

• 5.3 L

• 9.33 L

• 13.7 L

• 45 L

Avogadro's : Extra Practice

​Link

https://www.youtube.com/watch?v=MfqTR_llVVc

Copyright © 2011 - MsRazz ChemClass

Ideal Gas Law

Where,
P= pressure (atm)
V= volume (L)
n= moles (mol)
R= 0.0821 L·atm/mol·K
T= temperature (K)

PV=nRT

​REMINDER:

We want our other variables to MATCH the R constant units

SOMETIMES conversions are needed

​On the back of your periodic table

Example Problem:

At what temperature would 52.3g of
methane (CH4) gas occupy 65.7L at 184atm?
P=
V=
n=
R=
T=

​Work this question out, be ready to answer it on the next slide

​REMINDER- When a question says GRAMS you will use molar mass

Multiple Choice

At what temperature would 52.3g of methane (CH4) gas occupy 65.7L at 184atm?

• 4518 Celcius

• 45187 K

• 451 K

• 425 K

Ideal Gas Law: Extra Practice

​Link

Regular

• https://www.youtube.com/watch?v=TqLlfHBFY08

Uses molar mass

• https://www.youtube.com/watch?v=0VaupcMr3oQ

Boyle’s→ Volume ∝ 1 ⁄ pressure

P1V1=P2V2

Charles’→ Volume ∝ Temperature

V1 V2
T1 T2

Gay-Lussac’s → Pressure ∝

Temperature

P1 P2
T1 T2

V1 V2
n1 n2

=

=

=

PV=nRT

Avogadro’s→ Volume ∝ Moles

Ideal Gas Law