http://teachers.yourhomework.com/blowe/ 1

Today's Agenda .t 1/18/11Recall 1Get your comp books out before the bell rings

Start Semester ReviewPass out semester review

Start studying for the Chem department final which will be on Monday January 24, 2011. There will be another class final as well.Make sure to have a good book to read and pass time.

04/18/23

Chemistry Department Final

The Chemitry department final is on Monday January 24th.

There will be an additional Chem test on your “final” day based on material this semester.

04/18/23

Recall

Moles(mol)

Mass(g)

Molar Mass(g/mpl)

04/18/23

N2 H2 NH3

14.01+3(1.008)=17.034

2(1.008)=2.016

2(14.01)=28.02

6.78

€

6.78

28.02= .24 .24

€

⋅3

1= .72 .24

€

⋅2

1= .48

.72 x 2.016= 1.45

.48 x 17.034= 8.18

6.78 g of N2 N2 + 3H2 2 NH3

Recall 2

Find the mole ratios in:

2Al + 6HCl 2AlCl3 + 3H2

1.From HCl to H2

2.From Al to AlCl3

3.From H2 to HCl

4.From AlCl3 to H2

04/18/23

3/6

2/2

6/3

3/2

Scientific Notation

When the number is Big• Leave one number in front of

the decimal point and count how many steps you took to get there.

• Then times that number by 10 to the power of the (+) number of steps to get there.

• 7,980,000 7.98 x 10+

When the number is Small• Leave one number in front of

the decimal point and count how many steps you took to get there.

• Then times that number by 10 to the power of the (-) number of steps to get there.

• 0.000026 2.6 x 10-

04/18/23

From Standard to Scientific

Scientific Notation• Look at the exponent on 10

• If the exponent is positive (+), then move the decimal point that # of steps to the right. Put in zeros where there are no numbers

• ex. 6.7 x 103 m

• = 6700 m

• If the exponent is negative (-), then move the decimal point that # of steps to the left and place zeros as place holders.

• Ex. 3.4 x 10-5 g

• = 0.000034 g

From Scientific to Standard

Metric ConversionsRemember the prefixes for the metric system.

The most used are:

• μ micro 10-6

• m milli 10-3

• c centi 10-2

• k kilo 103

04/18/23

Example:5 cm = ? m5 x 10-2 m = 0.05 m

2400 mg = ? kg2400 x 10-3 g = ? 103 g

2400 x 10-3 /103 kg2400 x 10-6 kg=.0024 kg

Metric Conversions

There are many different ways to do metric conversions.

Find the one that you like the most and stick with it.

• Remember the step method.

• What you have divided by what you need.

04/18/23

Temperature Conversions

To Fahrenheit from Celsius

F = C x (9/5) + 32

Example:

What is 32°C in °F?

F = 32 x (9/5) + 32

F = 57.6 + 32

F = 89.6°F

To Celsius from Fahrenheit

C = (F - 32) x (5/9)

Example:

What is 75°F in °C?

C = (75 - 32) x (5/9)

C = (43) x (5/9)

C = 23.9°C04/18/23

Temperature Conversionsto Kelvin

To Kelvin from Celsius

K = C + 273

Example:

What is 32°C in K?

K = 32 + 273

K = 305 K

To Celsius from Kelven

C = K - 273

Example:

What is 50 K in °C?

C = 50 – 273

C = -223°C

04/18/23Always change from Fahrenheit to Celsius then to Kelvin

Dimensional analysisVolume = How much space something takes up

Mass = How much something weighs

Density = Mass/Volume

Example:

A block of Aluminum is 3 cm x 4 cm x 5 cm and has the density of 2.7 g/cm3. What is the mass of this block?

Volume is 3 x 4 x 5 = 60 cm3

Mass = Density x volume

Mass = 2.7 g/cm3 x 60 cm3 = 162 g

Dimensional analysisGraduated cylinders can be used to find the

volume of an object.

Volume = Final measurement – Initial measurement

Example:

A graduated cylinder first measures 40 mL. After an object is dropped in it then reads 62 mL. What is the volume of the object?

V= 62 – 40 = 22 mL

BTW mL = cm3

HomeworkBegin to start reviewing for the semester final

Some strategies that may help:

• Read over your notebook

• Try and find the chapters in the book that correspond to your notes and practice questions.

• Go over recalls and examples in your notebook

• Take time to memorize names like the difference between Nitrate and Nitride!

http://teachers.yourhomework.com/blowe/ 1304/18/23