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Moles

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………………………………………………………………………………

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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
(edited 12 years ago)
Original post by charco
All mistakes highlighted in red


Whats wrong with the grams please?
Original post by JamesNeedHelp2
Whats wrong with the grams please?


you are asked for the answer in moles ...
Reply 4
Original post by JamesNeedHelp2
Whats wrong with the grams please?


they'r the moles ur after LOL...
Original post by charco
you are asked for the answer in moles ...


Whats the unit for moles bro? im new to this thing
Reply 6
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.
Original post by F1Addict
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?
:smile:
Original post by JamesNeedHelp2
ooh. alright thanks. But what if they ask me to calculate mass, will the unit be grams?


:smile:
Reply 9
Original post by JamesNeedHelp2
ooh. alright thanks. But what if they ask me to calculate mass, will the unit be grams?

Yep.
Original post by charco
:smile:

:smile:


Thank you for the help.
Original post by F1Addict
Yep.


Thank you for the help +rep
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
Original post by F1Addict
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
Original post by charco
:smile:

:smile:


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
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 :smile: :smile:
Original post by charco
1 mole of Cl2 is usually taken as 71 (2 x 35.5) otherwise :smile: :smile:


Thanks man really appreciated.
Original post by charco
1 mole of Cl2 is usually taken as 71 (2 x 35.5) otherwise :smile: :smile:


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:smile:
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:smile:


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
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

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