Transcript Slide 1

Ch10.1 – The Mole
1 mol = 6.02 x 1023 particles
This is called Avogadro’s Number
*Think of it as a chemist’s dozen
(A dozen donuts or a mole of donuts?)
Can be used for atoms, ions, molecules, donuts, oranges,
grains of sand, chevys, etc.
Why that number?
-Since 1 amu = 1.66 x 10-24g:
.000 000 000 000 000 000 000 00166
x 602 000 000 000 000 000 000 000
=1
The Mole
•Can use as a unit for counting numbers
•Atoms are too small to count individually and there are too many, so we need a
way to bundle a bunch, like having a dozen oranges = 12 oranges
•1 mole = 6.02 x 1023 particles
•This is hard to understand, so let’s relate it.
Did You Know???
1. A grain of rice has an average mass of 1.75 x 10-5kg.
What is the mass of one mole, 6.02 x 1023, grains of rice?
1.05 x 1019 kilograms
This is hard to understand, so let’s change this mass to the mass of cars.
This would require a million cars per person to equal this mass!!
2. You can count the number of oranges in 6 dozen in a few minutes.
Six moles of oranges would have a mass as large as the entire Earth!
3. Avogadro’s number (1 mole) is so large, if you could count 100 particles every
minute and counted 12 hrs every day, and had every person on Earth also
counting, it would take more than 4 million years to count a mole of anything!
4. To obtain Avogadro’s number in grains of sand, it would be necessary to dig up
the entire surface of the Sahara Desert, an area of 8 x 106km2 (an area slightly
less than the area of the U.S.), to a depth of 200m.
Conversions:
1 mol
6.02 x 1023 particles
or 6.02 x 1023 particles
1 mol
Ex 1) How many moles of Mg are 3.01 x 1022 atoms?
Ex 2) How many molecules are 4.00 mol of glucose, C6H12O6?
HW #2) How many atoms are 0.360mol of Silver?
Gram Formula Mass
Ex3)
He weighs
C weighs
or
or
The mole # was chosen so that the # on the Periodic Table
can be read in grams.
*Round masses to nearest 1/10*
Ex4)H 1.0079
F 18.998403
Cl 35.453
Ex5) Find the molecular mass of:
H2O
NaCl
Mg3 (PO4)2
Ch 10 HW #1 1 – 7
Ch10 HW#1 1 – 7
1) How many moles in 2.80 x 1024 atoms of silicon?
3) How many oxygen atoms in each:
A) NH4NO3
B) C9H8O4
C) O3
D) C3H5(NO3)3
Ch10 HW#1 1 – 7
1) How many moles in 2.80 x 1024 atoms of silicon?
2.80 x 1024 atoms 1 moles
= 4.65 moles
6.02 x 1025 atoms
2) (In class)
3) How many oxygen atoms in each:
A) NH4NO3
B) C9H8O4
C) O3
D) C3H5(NO3)3
Ch10 HW#1 1 – 7
1) How many moles in 2.80 x 1024 atoms of silicon?
2.80 x 1024 atoms 1 moles
= 4.65 moles
6.02 x 1025 atoms
2) (In class)
3) How many oxygen atoms in each:
A) NH4NO3
3
B) C9H8O4
4
C) O3
3
D) C3H5(NO3)3
9
4) How many molecules in 2.14 mol CO?
5) How many moles in 4.65 x 1024 molecules of NO2?
4) How many molecules in 2.14 mol CO?
23
2.14 mol CO 6.02 x 10 molecules
= 1.29 x 1024 molecules
1 mol CO
5) How many moles in 4.65 x 1024 molecules of NO2?
4) How many molecules in 2.14 mol CO?
23
2.14 mol CO 6.02 x 10 molecules
= 1.29 x 1024 molecules
1 mol CO
5) How many moles in 4.65 x 1024 molecules of NO2?
4.63 x 1024 molecules
1 moles
= 7.72 moles
6.02 x 1023 molecules
6) Gram molecular mass
A. C2H6
C. C3H7OH
B. PCl3
D. N2O5
6) Gram molecular mass
A. C2H6
2 C @ 12.0 = 24.0
6 H @ 1.0 = 6.0
30.0 g/mol
B. PCl3
1 P @ 31.0 = 31.0
3 Cl @ 35.5 = 106.5
137.5 g/mol
C. C3H7OH
D. N2O5
6) Gram molecular mass
A. C2H6
2 C @ 12.0 = 24.0
6 H @ 1.0 = 6.0
30.0 g/mol
C. C3H7OH
3 C @ 12.0 = 36.0
8 H @ 1.0 = 8.0
10 @ 16.0 = 16.0
60.0 g/mol
B. PCl3
1 P @ 31.0 = 31.0
3 Cl @ 35.5 = 106.5
137.5 g/mol
D. N2O5
2 N @ 14.0 = 28.0
5 O @ 16.0 = 80.0
108.0 g/mol
7) Gram Formula Mass
A. Sr(CN)2
C. Al2(SO3)3
B. NaHCO3
7) Gram Formula Mass
A. Sr(CN)2
1 Sr @ 87.6 = 87.6
2 C @ 12.0 = 24.0
2 N @ 14.0 = 28.0
139.6
g/
mol
C. Al2(SO3)3
B. NaHCO3
7) Gram Formula Mass
A. Sr(CN)2
1 Sr @ 87.6 = 87.6
2 C @ 12.0 = 24.0
2 N @ 14.0 = 28.0
139.6
g/
mol
C. Al2(SO3)3
B. NaHCO3
1 Na @ 23.0 = 23.0
1 H @ 1.0 =
1.0
1 C @ 12.0 = 12.0
3 O @ 16.0 = 48.8
83.8 g/mol
7) Gram Formula Mass
A. Sr(CN)2
1 Sr @ 87.6 = 87.6
2 C @ 12.0 = 24.0
2 N @ 14.0 = 28.0
139.6
g/
mol
C. Al2(SO3)3
2 Al @ 27.0 = 54.0
3 S @ 32.1 = 96.3
9 O @ 16.0 = 144.0
294.3 g/mol
B. NaHCO3
1 Na @ 23.0 = 23.0
1 H @ 1.0 =
1.0
1 C @ 12.0 = 12.0
3 O @ 16.0 = 48.8
83.8 g/mol
Ch10.2 – Mole/Mass Conversions
Ex 1) How many grams are in 7.20 mol of dinitrogen trioxide?
Ex 2) How many grams are in 3.41 mol of calcium oxide?
Ex 3) Find the number of moles in 92.81g of Iron (III) Oxide?
Ch10.2 – Mole/Mass Conversions
Ex 1) How many grams are in 7.20 mol of dinitrogen trioxide?
7.20 mol N2O3 76.0 grams N2O3
= 547 grams N2O3
1 mol N2O3
2 N @ 14.0 = 28.0
3 O @ 16.0 = 48.0
76.0 g/mol
Ex 2) How many grams are in 3.41 mol of calcium oxide?
= 191 grams CaO
Ex 3) Find the number of moles in 92.81g of Iron (III) Oxide?
= .581 Moles
HW#8) Find the mass of each:
a) 0.720 mol Be
b) 2.40 mol N2
(finish c, d)
HW#9) Find # of moles in each:
b) 0.000264g Li2HPO4
(finish #9)
Ch 10 HW#2 8, 9
Ch3 X.C.
Average Density of Earth.
Given: DiameterE = 12,756 km
MassE = 5.98x1024 kg
VolumeΘ = 4/3 πr3
RadiusE = DiameterE = 12756 km = 6378 km = 637,800,000 cm
2
2
VolumeE = 4/3.πr3 = 4/3.π(637,800,000 cm)3 = 1.09x1027 cm3
MassE = 5.98 x 1024 kg
5.98 x 10 27 g
m
5.98 x 1027g
3
D=
=
=
5.50
g/cm
V
1.09 x 1027 cm3
Ch10 HW#2 8 – 9
8c) Convert to mass:
10.0 mol Cr
d)
3.32 mol K
Ch10 HW#2 8 – 9
8c) Convert to mass:
10.0 mol Cr
d)
52.0g Cr
1 mol Cr
3.32 mol K 39.1 g K
1 mol K
= 520g Cr
= 130 g K
Ch10 HW#2 8 – 9
8c) Convert to mass:
10.0 mol Cr
d)
9) Find moles
a) 5.00g H2
c) 72.0g Ar
d) 3.70x10 -1 g
52.0g Cr
1 mol Cr
3.32 mol K 39.1 g K
1 mol K
= 520g Cr
= 130 g K
Ch10 HW#2 8 – 9
8c) Convert to mass:
10.0 mol Cr
d)
52.0g Cr
1 mol Cr
3.32 mol K 39.1 g K
1 mol K
9) Find moles
a) 5.00g H2 1 mol H2
2.0 g H2
= 2.5 mol H2
c) 72.0g Ar 1 mol Ar
39.9g Ar
= 1.80 mol Ar
d) 3.70x10 -1 g 1 mol B
10.8g B
=
= 520g Cr
= 130 g K
Ch10.3 – Using the Mole
Ex) What is the mass of 3.01x1023 atoms of Carbon?
Ex) What is the mass of 12.04x1023 molecules of oxygen?
Ex) How many molecules are there in 63.8g of ethanol, CH3OH?
Ch10 HW #3 (10-12)
Ch10.3 – Using the Mole
Ex) What is the mass of 3.01x1023 atoms of Carbon?
3.01x1023 atoms C 1 mol C
12.0 g C
6.02x1023 atoms C 1 mol C
= 6.00g C
Ex) What is the mass of 12.04x1023 molecules of oxygen?
12.04x1023 molecules O2
1 mol O2
32.0g O2
6.02x1023 molec. O2 1 mol O2 = 64.0g O2
Ex) How many molecules are there in 63.8g of ethanol, CH3OH?
63.8g CH3OH 1 mol CH3OH 6.02 x 1023 molecules CH3OH
32.0g CH3OH
1 mol CH3OH
= 1.20 x 1024 molecules CH3OH
Ch10 HW #3 (10-12)
Lab10.1 – Molar Mass
- due tomorrow
- Ch10 HW#3 due at beginning of period
Ch10 HW #3 10 – 12
10) What is the mass of 2.11 x 1024 molecules of sulfur dioxide?
2.11 x 1024 molecules SO2
1 S @ 32.1 = 32.1
2 0 @ 16 = 32.0
64.1 g/mol
10) What is the mass of 2.11 x 1024 molecules of sulfur dioxide?
2.11 x 1024 molecules SO2 1 moles SO2 64.1g SO2
= 224g SO2
23
6.02 x 10
1 moles SO2
molecules SO2
1 S @ 32.1 = 32.1
2 0 @ 16 = 32.0
64.1 g/mol
11) What is the mass of 1.0 x 1022 molecules of iodine?
1.0 x 1022 molecules I2
2 I @ 126.9 = 253.8 g/mol
11) What is the mass of 1.0 x 1022 molecules of iodine?
1.0 x 1022 molecules I2
1 moles I2
1023
253.8g I2
6.02 x
1 moles I2
molecules I2
= 4.22g I2
2 I @ 126.9 = 253.8 g/mol
12) How many molecules is 126.7g of sucrose?
126.7g C6H12O6
6 C @ 12.0 = 72.0
12 H @ 1.0 = 12.0
6 O @ 16.0 = 96.0
180.0 g/mol
12) How many molecules is 126.7g of sucrose?
6.02 x 1023
126.7g C6H12O6 1 mol C6H12O6 molecules C H O
6 12 6
180.0g C6H12O6 1 mol C6H12O6
23
=
4.23
x
10
6 C @ 12.0 = 72.0
molecules C6H12O6
12 H @ 1.0 = 12.0
6 O @ 16.0 = 96.0
180.0 g/mol
Ch10.4 – Volume of a Mole of Gas
Volumes of gases can change a lot, if temp or pressure change.
Standard temperature and pressure: (STP)
Temp: 0°C (273K)
Pressure: 101.3 kPa (kiloPascals) or 1 atmosphere
At STP, 1 mole of any gas occupies a volume of 22.4 Liters.
22.4 L or 1 mol
22.4 L
1 mol
Ch10.4 – Volume of a Mole of Gas
Volumes of gases can change a lot, if temp or pressure change.
Standard temperature and pressure: (STP)
Temp: 0°C (273K)
Pressure: 101.3 kPa (kiloPascals) or 1 atmosphere
At STP, 1 mole of any gas occupies a volume of 22.4 Liters.
22.4 L or 1 mol
22.4 L
1 mol
Ex 1) What is the volume of 0.600 mol of SO2 gas at STP?
Ch10.4 – Volume of a Mole of Gas
Volumes of gases can change a lot, if temp or pressure change.
Standard temperature and pressure: (STP)
Temp: 0°C (273K)
Pressure: 101.3 kPa (kiloPascals) or 1 atmosphere
At STP, 1 mole of any gas occupies a volume of 22.4 Liters.
22.4 L or 1 mol
22.4 L
1 mol
Ex 1) What is the volume of 0.600 mol of SO2 gas at STP?
0.600 mol SO2 22.4 L SO2
1 mol SO2
= 13.4 L SO2
Ex 2) Determine the # of moles in 33.6 L of He gas at STP:
Ex 3) The density of a gaseous compound of C and O is 1.964 g/L
at STP. Determine the gram formula mass. Is it CO or CO2?
CO: 1 C @ 12.0 = 12.0
CO2: 1 C @ 12.0 = 12.0
1 O @ 16.0 = 16.0
2 O @ 16.0 = 32.0
20.0 g/mol
44.0 g/mol
Ex 2) Determine the # of moles in 33.6 L of He gas at STP:
1.964g 1 mol He = 1.50 mol He
1 L 22.4 L He
Ex 3) The density of a gaseous compound of C and O is 1.964 g/L
at STP. Determine the gram formula mass. Is it CO or CO2?
CO: 1 C @ 12.0 = 12.0
CO2: 1 C @ 12.0 = 12.0
1 O @ 16.0 = 16.0
2 O @ 16.0 = 32.0
20.0 g/mol
44.0 g/mol
Ex 2) Determine the # of moles in 33.6 L of He gas at STP:
1.964g 1 mol He = 1.50 mol He
1 L 22.4 L He
Ex 3) The density of a gaseous compound of C and O is 1.964 g/L
at STP. Determine the gram formula mass. Is it CO or CO2?
1.964g 22.4 L
1 L 1 mol
= 44.0 g/mol
CO: 1 C @ 12.0 = 12.0
CO2: 1 C @ 12.0 = 12.0
1 O @ 16.0 = 16.0
2 O @ 16.0 = 32.0
20.0 g/mol
44.0 g/mol
Ex4) 10.4g of dry ice, CO2 , is allowed to sublime into a gas.
If the gas is brought to STP, what volume does it occupy?
Ex5) 1.13x1022 molecules of hydrogen gas occupy what volume
at STP?
Ex4) 10.4g of dry ice, CO2 , is allowed to sublime into a gas.
If the gas is brought to STP, what volume does it occupy?
10.4g CO2
1 mol CO2
22.4L CO2
44.0g CO2
1 mol CO2
= 5.29L CO2
Ex5) 1.13x1022 molecules of hydrogen gas occupy what volume
at STP?
Ex4) 10.4g of dry ice, CO2 , is allowed to sublime into a gas.
If the gas is brought to STP, what volume does it occupy?
10.4g CO2
1 mol CO2
22.4L CO2
44.0g CO2
1 mol CO2
= 5.29L CO2
Ex5) 1.13x1022 molecules of hydrogen gas occupy what volume
at STP?
1.13x1022
molecules H2
1 mol H2
6.02x1023
22.4L H2
1 mol H2
= .420L H2
molecules H2
Ch 10 HW #4 13-18
Ch 10 HW#4 13-18
( XC for correct #16 )
13) 3 balloons each contain the same # of molecules of 3 different gases @ STP.
Same mass? Same volume?
CO2
O2
H2
Ch 10 HW#4 13-18
( XC for correct #16 )
13) 3 balloons each contain the same # of molecules of 3 different gases @ STP.
Same mass? Same volume?
CO2
O2
H2
Diff mass
Same volume
14) Volume @ STP
a) 3.20x10-3 mol CO2
b) 0.960 mol CH4
c) 3.70 mol N2
15) At STP, how many moles?
a) 67.2L SO2
b) 0.880L He
c) 1.00x103L C2H6
14) Volume @ STP
a) 3.20x10-3 mol CO2 22.4L CO2
1 mol CO2
b) 0.960 mol CH4 22.4L CH4
1 mol CH4
c) 3.70 mol N2 22.4L N2
1 mol N2
15) At STP, how many moles?
a) 67.2L SO2 1 mol SO2
22.4 L SO2
b) 0.880L He 1 mol He
22.4 L He
c) 1.00x103L C2H6 1 mol C2H6
22.4 L C2H6
= .0717l CO2
= 21.5L CH4
= 82.9L N2
=
=
=
14) Volume @ STP
a) 3.20x10-3 mol CO2 22.4L CO2
1 mol CO2
b) 0.960 mol CH4 22.4L CH4
1 mol CH4
c) 3.70 mol N2 22.4L N2
1 mol N2
15) At STP, how many moles?
a) 67.2L SO2 1 mol SO2
22.4 L SO2
b) 0.880L He 1 mol He
22.4 L He
c) 1.00x103L C2H6 1 mol C2H6
22.4 L C2H6
= .0717l CO2
= 21.5L CH4
= 82.9L N2
= 3.00 mol SO2
= .0393 mol He
= 44.6 mol C2H6
16) AT STP what volume does 12.2g fluorine gas occupy?
12.2 g F2 1 mol F2 22.4 L F2
38.0 g F2 1 mol F2
=
17) 13.0 x 1024 molecules of Argon occupy what volume at STP?
13.0 x 1024
molecules Ar 1 mol Ar
22.4 L Ar
6.02 x 1023
1 mol Ar
molecules Ar
=
16) AT STP what volume does 12.2g fluorine gas occupy?
12.2 g F2 1 mol F2 22.4 L F2
38.0 g F2 1 mol F2
= 7.19 L F2
17) 13.0 x 1024 molecules of Argon occupy what volume at STP?
13.0 x 1024
molecules Ar 1 mol Ar
22.4 L Ar
6.02 x 1023
1 mol Ar
molecules Ar
=
16) AT STP what volume does 12.2g fluorine gas occupy?
12.2 g F2 1 mol F2 22.4 L F2
38.0 g F2 1 mol F2
= 7.19 L F2
17) 13.0 x 1024 molecules of Argon occupy what volume at STP?
13.0 x 1024
molecules Ar 1 mol Ar
22.4 L Ar
6.02 x 1023
1 mol Ar
molecules Ar
= 484 L Ar
18) The densities of 3 gases:
A: 1.25 g/L
B: 2.86 g/L
C:0.714 g/L
Calculate the gFm of each (g/mol)
ID as NH3, SO2, Cl2, N2, or CH4
A) 1.25 g 22.4 L
1L
1 mol
=
B) 2.86 g 22.4 L
1L
1 mol
=
C) 0.714 g 22.4 L
1L
1 mol
=
NH3:
Cl2:
1N @ 14.0 = 14.0
3N @ 1.0 = 3.0
17.0 g/mol
1 S @ 32.1 = 32.1
2 O @ 16.0 = 32.0
64.1 g/mol
2 Cl @ 35.5 = 71.0 g/mol
N2:
2 N @ 14.0 = 28.0 g/mol
CH4:
1 C @ 12.0 = 12.0
4 N @ 1.0 = 4.0
16.0 g/mol
SO2:
18) The densities of 3 gases:
A: 1.25 g/L
B: 2.86 g/L
C:0.714 g/L
Calculate the gFm of each (g/mol)
ID as NH3, SO2, Cl2, N2, or CH4
A) 1.25 g 22.4 L
1L
1 mol
= 28.0 g/mol Cl2:
1N @ 14.0 = 14.0
3N @ 1.0 = 3.0
17.0 g/mol
1 S @ 32.1 = 32.1
2 O @ 16.0 = 32.0
64.1 g/mol
2 Cl @ 35.5 = 71.0 g/mol
N2:
2 N @ 14.0 = 28.0 g/mol
CH4:
1 C @ 12.0 = 12.0
4 N @ 1.0 = 4.0
16.0 g/mol
B) 2.86 g 22.4 L
1L
1 mol
= 64.1 g/mol
C) 0.714 g 22.4 L
1L
1 mol
= 16.0 g/mol
NH3:
SO2:
Ch10.5 – More Conversions
Ex1) One copper cylinder from the last lab had a mass of 57.68g.
How many copper atoms is that?
Ex2) Dinitrogen monoxide is stored in a 2.00 L cylinder at STP.
What mass is this?
Ch10.5 – More Conversions
Ex1) One copper cylinder from the last lab had a mass of 57.68g.
How many copper atoms is that?
57.68g Cu 1 moles Cu 6.02x1023 atoms
63.5g Cu
1 moles Cu
= 5.47x1023 atoms Cu
Ex2) Dinitrogen monoxide is stored in a 2.00 L cylinder at STP.
What mass is this?
2.00 L N2O 1 moles N2O 44.0 g N2O
22.4 L N2O 1 moles N2O
= 3.93 g N2O
Ex3) Hydrogen sulfide is a dangerous gas released in volcanoes.
If a scientist collects 10.0 mL sample at STP,
how many gas particles are present?
Ex3) Hydrogen sulfide is a dangerous gas released in volcanoes.
If a scientist collects 10.0 mL sample at STP,
how many gas particles are present?
.0100L H2S 1 mole H2S 6.02x1023 particles H2S
22.4 L H2S 1 moles H2S
= 2.69x1020 particles
Ch10 HW#4 Mid Ch Rev Problems
Lab9.1 – Formulas and Oxidation Numbers Review
- due 2 days
- Mid Ch Rev due at beginning of period
Ch10 Mid Chapter Review
1. How many atoms are in 1.23 moles of calcium?
2. How many grams are in 1.23 moles of calcium?
3. How many moles of carbon are in 5.5 g sample of carbon?
4. How many moles of aluminum are there in 2.3x1024 atoms?
5. How many liters are in 2.50 moles of hydrogen molecules, H2?
6. How many moles are in 3.04 liters of chlorine gas?
7. How many particles are in 55.6 g of calcium oxide?
8. How many liters of gas are produced when 10.3 g of dry ice,
solid carbon dioxide, sublimes?
Ch10 Review
1) How many moles in 1.50x1023 molecules NH3?
2) Calculate the gram formula mass of H3PO4.
3 H@
1P@
4O@
3) How many moles in 15.5 g SiO2?
Ch10 Review
1) How many moles in 1.50x1023 molecules NH3?
1.50x1023 molecules NH3 1 mol NH3
6.02x1023 molecules NH3
2) Calculate the gram formula mass of H3PO4.
3 H@ 1.0 = 3.0
1 P @ 31.0 = 31.0
= 98.0 g/mol
4 O @ 16.0 = 64.0
3) How many moles in 15.5 g SiO2?
=.249 moles
NH3
3) How many moles in 15.5 g SiO2?
4) Find the mass of 1.50 moles C5H12
3) How many moles in 15.5 g SiO2?
15.5 g SiO2 1 mol SiO2
60.1 g SiO2
= .257 mol SiO2
4) Find the mass of 1.50 moles C5H12
1.50 moles C5H12 72.0 g C5H12
1 mol C5H12
= 108 g C5H12
5) Calculate the volume of 7.6 mole Ar at STP.
6) Find the volume of 835 g SO3 at STP.
5) Calculate the volume of 7.6 mole Ar at STP.
7.6 mol Ar 22.4 L Ar
1 mol Ar
= 170 L Ar
6) Find the volume of 835 g SO3 at STP.
835g SO3 1 mol SO3 22.4 L SO3
80.1 g SO3 1 mol SO3
= 234 L SO3
Chapter 10 Hw #4 19 – 22
19) Mass in grams of an atom of Hg?
1 atom Hg
1 mol Hg
200.6g Hg
6.02x1023 atoms Hg 1 mol Hg
= 3.33x10-22 g
20) How many molecules are in a 4.00 L balloon (at STP) filled with carbon dioxide?
Would the answer change if CO?
9.00L CO2 1mol CO2
6.02x1023 molecules
22.4 L CO2
1 mol CO2
= 2.42x1023 molecules
21) % comp
a) 9.03g Mg with 3.48g N
9.03g Mg
12.51g total
x100%
B) 29.0g Ag with 4.30g S
29.0g Ag
33.30g total
x100%
= 72%
3.48g N
12.51g total
x100%
= 28%
= 87%
4.30g S
33.30g total
x100%
= 13%
22) % comp of ethane C2H6
(assume 1 mol)
2 C @ 12.0 = 24.0
6 C @ 1.0 = 6.0
30.0 g/mol
C:
24.0g C
30.0g total x100%
H:
= 80%
6.0g H
30.0g total
x100% = 20%
Molarity
Molarity – a measure of concentration, represented with the symbol (M)
- defined as
Molarity (M) = Moles of Solute/Liter of solution
- solute
the substance added to the solution
Ex: NaCl added to pure water to make a salt water solution.
solute
solvent
- sometimes the solution is measured in dm3 instead
1L = 1 dm3
Ex) What is the molarity of a solution made by dissolving 45.2g of Ca(OH)2 in
250 mL of solution?
45.2 Ca(OH)2 1 mol Ca(OH)2
74.0g Ca(OH)2
= .611 mL Ca(OH)2
1 Ca @ 40.1 = 40.1
2 O @ 16.0 = 32.0
KHDUdcm
.611mL
2 H @ 1.0 = 2.0
250mL = .250 L
.250 L
=2.44 M Ca(OH)2
74.0 g/mol
Ex) What is the molarity of a solution made by dissolving 10g of potassium chloride in
0.505 dm3 of solution?
10g KCl 1 mol KCl
74.6g KCl
= .134 mol KCl
= .265 M KCl
.505 L
1 K @ 39.1 = 39.1
1 Cl @ 35.5 = 35.5
74.6