convert the following:

1. 4.0 x 106 0.02 = _____

2. Find the gfw of KOH

3. How many grams are in 0.10 moles of KOH?

4. ACT-prep question:1. The moon rotates once while

going around the earth once. As a result.a) the moon follows an elliptical

path

b) The sun is eclipsed by the moon every seven years.

c) Only one side of the moon faces the Earth.

d) Every fourth year is a leap year.

Quiz:March 3, 2005

2 x 108

K = 39 amu, 0 = 16 amu, H = 1 amu1(39) + 1(16) + 1(1) =56 amuor 56 g/mole

0.10 moleKOH_56g KOH_ 1mole KOH

5.6 g KOH

Molarity = moles solute Liter of solution

Molarity = moles solute dm3 of solution

HW 16: #42 49 page 205; #95, 98 page 218; H#96,100Should be completed today!Tonight’s e.c. HW is # 17

http://www.uccs.edu/~tchriste/courses/PES105/105lectures/105lecmotions.htmlhere’s a link for anyone interested in planetary motions and the relationshipbetween the earth and sun.

What is the molarity of a solution made from 2.0 g Ca(OH)2 in 500cm3.

Underline theimportant

information.

What is the definition ofMolarity?

M = moles dm3

M =2.0 g Ca(OH)2

500 cm3

?grams moles1000 cm3 dm3

1000 cm3

1dm3

Ca = 40.02H = 2(1)O= 2(16) 74 g/mole Ca(OH)2

1mole Ca(OH)2

74 g Ca(OH)2

Multiply the Numerator –

Divide theDenominator

Since you don’t have molesor dm3, look for units that caneasily be converted to moles or to dm3

0.054 mole/dm3

or 0.054 M Ca(OH)2

0.3 moles

dm3

129.5 g NiCl2

mole NiCl2

Describe the preparation of the following solution: 1.00 dm3 of 0.3M NiCl2

Underlineimportant

information

Use the quantity ofthe givensolution

asnumerator

To figureout what

to do with 0.3M, you needto know what

it means! 1.00 dm3

M = moles dm3

Since you can’t measure

out a mole,you will

need to findgrams.

Find gfw ofNiCl2

Ni =58.72 Cl = 2(35.4)129.5 g/mole

Dissolve 38.8 g NiCl2 in enough water to geta volume of 1.00 dm3

0.400 moles

dm3

129.5 g NiCl2

mole NiCl2

Describe the preparation of the following solution: 2.50 x 103 cm3 of 0.400M NiCl2

Underlineimportant

information

Use the quantity ofthe givensolution

asnumerator

To figureout what

to do with 0.3M, you needto know what

it means!

2.50 x 103 cm3 = 2500 cm3 = 2.50 dm3

1000 cm3/dm3

M = moles dm3

Since you can’t measure

out a mole,you will

need to findgrams.

Find gfw ofNiCl2

Ni =58.72 Cl = 2(35.4)129.5 g/mole

Dissolve 130 g NiCl2 in enough water to geta volume of 2.50 dm3

2.50 dm3

Convertcm3 todm3

formulaunits

atoms

grams

MOLE

ions

gram formula weight

volume

16, #42 49 page 205; #95, 98 page 218; H#96,100First find moles, then find molarity.

• Each Group of two students will come up to the board and explain one problem. This is required, and is worth 10 points. We have no more than 2 days to do this.

• EXTRA CREDIT ASSIGNMENT:

• Build a mobile showing all of the conversions which are possible from moles to other units. The mobile must be attractive and helpful from 10 feet away. This is worth 25 points.

6.02x 1023

molecules

M

HW 17: #50-55 page 208; #101p218

• % = the proportion out of 100 pieces

• If there were 100, how much would be …– In a package of M&Ms 15 were brown, 6 were

yellow, and 4 were blue. What % were brown?• 15 + 6 + 4 = total number of M&Ms = 25

• 15/25 = the fraction which are brown.

• 60% are brown

15 x 100%25

Find the % nitrogen in ammonia.

• NH3 = ammonia

http://www.ausetute.com.au/percentc.html Tutorial for extra help

N = 14.03H = 3 x 1.0 17.0 amu

14.0 amu N

17.0 amu NH3

100%

= 82.4% N inNH3

To find the % composition of H2O

• H = 2(1.01) • O = 16.0

• H2O = 18 g/mole

• % H = 0.112 x 100%

•11.2% H• % O = 0.889 x 100%

•88.9% O%H = 2.02 g H2

18 g/mole H2O

%O = 16.0 g O

18 g/mole H2O