# Moles

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#1
Can someone check if my answers are correct for these 5 questions? Thanks in advance

1) How many moles are there in each of the following?

a) 72 g of Mg

.......Moles=72g/24=3g...…

b) 4 kg of CuO

…………………Moles=4000g/80=50g…………………………………………………………………………

c) 39 g of Al(OH)3

………………………Moles=39g/78=0.5g……………………………………………………………………

d) 1 tonne of NaCl

………………1 tonne= 1000000g so Moles=1000000/78=12820g……………………………………………………………………………

e) 20 mg of Cu(NO3)2

……………1mg=0.001g so 20mg=0.02g Moles=0.02g/188=1g………………………………………………………………………………
0
9 years ago
#2
(Original post by JamesNeedHelp2)
Can someone check if my answers are correct for these 5 questions? Thanks in advance

1) How many moles are there in each of the following?

a) 72 g of Mg

.......Moles=72g/24=3g...…

b) 4 kg of CuO

…………………Moles=4000g/80=50g…………………………………………………………………………

c) 39 g of Al(OH)3

………………………Moles=39g/78=0.5g……………………………………………………………………

d) 1 tonne of NaCl

………………1 tonne= 1000000g so Moles=1000000/78=12820g……………………………………………………………………………

e) 20 mg of Cu(NO3)2

……………1mg=0.001g so 20mg=0.02g Moles=0.02g/188=1g………………………………………………………………………………
All mistakes highlighted in red
1
#3
(Original post by charco)
All mistakes highlighted in red
Whats wrong with the grams please?
0
9 years ago
#4
(Original post by JamesNeedHelp2)
Whats wrong with the grams please?
2
9 years ago
#5
(Original post by JamesNeedHelp2)
Whats wrong with the grams please?
they'r the moles ur after LOL...
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#6
(Original post by charco)
Whats the unit for moles bro? im new to this thing
0
9 years ago
#7
(Original post by JamesNeedHelp2)
Whats the unit for moles bro? im new to this thing
Moles is the unit for moles. Its one of the 7 SI units.
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#8
Moles is the unit for moles. Its one of the 7 SI units.
ooh. alright thanks. But what if they ask me to calculate mass, will the unit be grams?
0
9 years ago
#9
(Original post by JamesNeedHelp2)
ooh. alright thanks. But what if they ask me to calculate mass, will the unit be grams?
1
9 years ago
#10
(Original post by JamesNeedHelp2)
ooh. alright thanks. But what if they ask me to calculate mass, will the unit be grams?
Yep.
1
#11
(Original post by charco)

Thank you for the help.
0
#12
Yep.
Thank you for the help +rep
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#13
(Original post by JamesNeedHelp2)
Thank you for the help +rep

2) What is the mass of each of the following?

a) 5 moles of Cl2 = 5 x 70=350g

b) 0.2 moles of Al2O3 = 0.2 x 102=20.4g

can you please check if this is correct also? Thanks
0
#14
Yep.
2) What is the mass of each of the following?

a) 5 moles of Cl2 = 5 x 70=350g

b) 0.2 moles of Al2O3 = 0.2 x 102=20.4g

can you please check if this is correct also? Thanks
0
#15
(Original post by charco)

2) What is the mass of each of the following?

a) 5 moles of Cl2 = 5 x 70=350g

b) 0.2 moles of Al2O3 = 0.2 x 102=20.4g

can you please check if this is correct also? Thanks
0
9 years ago
#16
(Original post by JamesNeedHelp2)
2) What is the mass of each of the following?

a) 5 moles of Cl2 = 5 x 70=350g

b) 0.2 moles of Al2O3 = 0.2 x 102=20.4g

can you please check if this is correct also? Thanks
1 mole of Cl2 is usually taken as 71 (2 x 35.5) otherwise
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#17
(Original post by charco)
1 mole of Cl2 is usually taken as 71 (2 x 35.5) otherwise
Thanks man really appreciated.
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#18
(Original post by charco)
1 mole of Cl2 is usually taken as 71 (2 x 35.5) otherwise
What is the mass of each of the following?

d) 0.002 moles of (NH4)2SO4 Mass=0.002x132=0.264g

e)0.3 moles of Na2CO3.10H2O Mass=0.002x256=0.512g

Can you please check these 2 last ones? Thank you so much
0
9 years ago
#19
(Original post by JamesNeedHelp2)
What is the mass of each of the following?

d) 0.002 moles of (NH4)2SO4 Mass=0.002x132=0.264g

e)0.3 moles of Na2CO3.10H2O Mass=0.002x256=0.512g

Can you please check these 2 last ones? Thank you so much
Mass of Na2CO3.10H2O = (2 x 23) + (12) + (3 x 16) + (10 x 18) = 286

0.3 moles = 0.3 x 286 = 85.8 g
0
#20
(Original post by charco)
Mass of Na2CO3.10H2O = (2 x 23) + (12) + (3 x 16) + (10 x 18) = 286

0.3 moles = 0.3 x 286 = 85.8 g
10H2O = 10 x 18

how did you get this please? since i got 10x2(1)

thank you for any further help
0
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