converting moles to atoms - chapter 3

7/29/2019 converting moles to atoms - chapter 3

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Chemistry January 15

Objective: To be able to change moles of an element

into numbers of atoms of the substance, and vice versa.

Preclass: See page 101 - 102 if you do not understand

this. Show all your work.

1. What is the mass of 5 moles ofsulfur?

2. What is the mass of 3.5 moles ofhydrogen?

3. How many moles are in 70.906 grams of chlorine?

4. How many moles are present in 14.042 grams of

silicon?


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2. What is the mass of 3.5 moles of

Hydrogen?

Given 3.5 moles H need molar mass of

H =

plan work. Set up conversion of moles to

mass to get mass as the answer

3.5 moles X gH1 mole H

cancel like units

multiply


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3. How many moles are in 70.906 grams of Chlorine?

given 70.906 g of Cl need molar mass of Cl = 35.45

plan work: change grams to moles, have to write 1 mole on

top and grams on bottom.

70. 906 g Cl X 1 mole Cl35.45 g Cl

cancel like units in numerator and denominator

Divide 70.906 by 35.45 =

4. How many moles are present in 14.042 grams of silicon?


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4. How many moles are present in 14.042 grams of silicon?


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1. What is the mass of 5 moles of sulfur?

2. What is the mass of 3.5 moles of

Hydrogen?

3. How many moles are in 70.906 grams ofChlorine?

4. How many moles are present in 14.042

grams of silicon?


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Jan 15, 2013

Objective: to be able to convert

moles to atoms and vice versa.

Class workCopy skills toolkitfrom page 103 into your

notebook."Determining number of

atoms from the amount in moles."


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Copy skills toolkit needed to find number

of atoms from amount in moles. See page

103 103


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Copy sample E page 103

You can shorten it a little.

Determine the number of atoms in 0.30 mol of fluorine atoms.

Gather info: F = .30 mol Find Number of atoms of FPlan: 1 mole is 6.022 X 10 23 atoms. select conversion factor

needed.

Calculate:

0.30 mole F X 6.022 X 10 23 atoms F

1mole F

Cancel like units and solve - multiply since all numbers are in

numerator.

= 1.8 X 10 23 atoms of F

Verify: Answer is less than 1 mole this makes sense.


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How to store Avogadro's number in your calculator

for later use.

Type the following 6.022

Press the 2nd key,

press the , key above which you see EE. This givesyou E

now type 23

you should see 6.022E23 now

type the store Key STO->

type Alpha key

then type A (seen above the math key)type enter.

Now see if it works try 2 X Alpha A you should

get 1.2044E24 which means 1.2044 X 10 24


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1. How many atoms in 0.70 moles

of iron?

0.70 moles Fe

0.70 mole Fe X 6.022 X 10 23atoms Fe

1mole Fe


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Switch problem around. Given atoms or

molecules how many moles do you have

Example Page 103 # 2,32. How many moles of silver are

represented by 2.888 X 1023 atoms?

2.888 X 10 23 atoms Ag X 1 mole Ag

6.022 X 1023

atoms

This is division:


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Example Page 103 # 3

3. How many moles of osmium are

represented by 3.5 X 1023 atoms?

3.5 X 10 23 atoms Os X 1 mole

6.022 X 10 23 atoms

This is division:


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Exit ticket:

Do this work on the looseleaf

1. What is Avogadro's number?

2. What is an amu?

3. What unit is mass measured in?

4. how many particles in a mole?


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exit ticket - work with the person who sits

beside you. Hand in one copy that both of

you have written on.

Solve these problems on page 109. Write

down the information given in each

roblem and then determine what formula

ou need to use. Show all your work.

51 a & b- 55 a & c


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Preclass:Do this work on the looseleaf

1. What is Avogadro's number?

2. What is an amu?

3. What unit is mass measured in?

4. how many particles in a mole?

Look at these problems on page 109. Write down the

information given in each problem and then determin

what formula you need to use for each one.

51 a,b,c, - 56


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Page 109 # 51 a

How many moles are represented

by each of the following.

a. 11.5 g Na which has an

atomic mass of 22.99 amu.

b.

c.


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Page 109 # 52 Determine the

mass in grams represented by

2.50 mol Tellurium

# 53.


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Do now

Do # 51 a,b,c 52, 53, 54, 55

a,b,c and56.


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If you can do all these try the rest 51 b,c, and 53,

& 54


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Do problems on page 103 # 1-3

1.

No homework: prepare for keystonetests. Buy your own calculator.

Also get lots of rest.


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converting moles to atoms - chapter 3