A sample of 0.500g of impure CaC03 was dissolved in 50.0cm³ of 0.100moldm–³ HCL and the remaining acid was titrated against 5.0cm³ of 0.12mol dm–³ NaOH solution. find the percentage of CaCO3 in the sample.

Really?

[quote author=immortalcrown]Really?[/quoteese]


yes bro, if you can help out, I appreciate.

zhukafa: A sample of 0.500g of impure CaC03 was dissolved in 50.0cm³ of 0.100moldm–³ HCL and the remaining acid was titrated against 5.0cm³ of 0.12mol dm–³ NaOH solution. find the percentage of CaCO3 in the sample.

typing...

zhukafa: A sample of 0.500g of impure CaC03 was dissolved in 50.0cm³ of 0.100moldm–³ HCL and the remaining acid was titrated against 5.0cm³ of 0.12mol dm–³ NaOH solution. find the percentage of CaCO3 in the sample.

pls wat do we call chem reactions dat release energy to the environment ..pls

valdprof: pls wat do we call chem reactions dat release energy to the environment ..pls

exothermic or exergonic reaction

zhukafa: A sample of 0.500g of impure CaC03 was dissolved in 50.0cm³ of 0.100moldm–³ HCL and the remaining acid was titrated against 5.0cm³ of 0.12mol dm–³ NaOH solution. find the percentage of CaCO3 in the sample.

Mole of acid used is. 50/1000*0.1
=0.005moles
No of mole of caco3
2HCL+CaCO3=CO2+CaCL2+H2O
2 mole of HCL=1 moles of CaCO3
0.005mole give 0.005/2 mole of CaCO3
0.0025 moles of cacO3
Mass of caCO3=0.0025*100
=0.25g
Thus, percentage =0.25/0.5
=0.5 *100%
=50%

What are the two subtance which when react with oxygen and atp produces light in fire flies??

Odilop:
What are the two subtance which when react with oxygen and atp produces light in fire flies??

Lmaooo!! Be nice.

zhukafa: A sample of 0.500g of impure CaC03 was dissolved in 50.0cm³ of 0.100moldm–³ HCL and the remaining acid was titrated against 5.0cm³ of 0.12mol dm–³ NaOH solution. find the percentage of CaCO3 in the sample.

IT'S LONG BUT GO THROUGH IT CAREFULLY
CaCO3 + 2HCl ----> CaCl2 + H2O + CO2 ------- eqn 1
Mole ratio 1 : 2
no of moles of HCl= (50/1000)*0.100= 0.005mol NOTE THAT THIS IS IN EXCESS

HCl + NaOH -------> NaCl + H2O ------------eqn 2
Mole ratio 1 : 1
no of moles of NaOH = (5.0/1000)*0.12= 0.0006 mol
from eqn 2, no of moles of HCl= 0.0006 mol
Actual no of moles of HCl that reacted in eqn 1 = Excess - Used
= 0.005mol - 0.0006mol
=0.0044mol
Back to eqn 1
CaCO3 + 2HCl ----> CaCl2 + H2O + CO2 ------- eqn 1
Mole ratio 1 : 2
no of moles x : 0.0044
x = (0.0044*1)/2 = 0.0022 mol
NOTE: 1 mol of CaCO3 = 100g
0.0022 mol of CaCO3 = 0.22g
% of CaCO3 in sample = (Mass of CaCO3/Mass of mixture)*100
= (0.22/0.500)*100
= 44%

oluafolabi:

Lmaooo!! Be nice.

how?

Dr_Bode:
IT'S LONG BUT GO THROUGH IT CAREFULLY
CaCO3 + 2HCl ----> CaCl2 + H2O + CO2 ------- eqn 1
Mole ratio 1 : 2
no of moles of HCl= (50/1000)*0.100= 0.005mol NOTE THAT THIS IS IN EXCESS

HCl + NaOH -------> NaCl + H2O ------------eqn 2
Mole ratio 1 : 1
no of moles of NaOH = (5.0/1000)*0.12= 0.0006 mol
from eqn 2, no of moles of HCl= 0.0006 mol
Actual no of moles of HCl that reacted in eqn 1 = Excess - Used
= 0.005mol - 0.0006mol
=0.0044mol
Back to eqn 1
CaCO3 + 2HCl ----> CaCl2 + H2O + CO2 ------- eqn 1
Mole ratio 1 : 2
no of moles x : 0.0044
x = (0.0044*1)/2 = 0.0022 mol
NOTE: 1 mol of CaCO3 = 100g
0.0022 mol of CaCO3 = 0.22g
% of CaCO3 in sample = (Mass of CaCO3/Mass of mixture)*100
= (0.22/0.500)*100
= 44%

thanks I appreciate. but how sure is your answer and workings.

Odilop:
Mole of acid used is. 50/1000*0.1
=0.005moles
No of mole of caco3
2HCL+CaCO3=CO2+CaCL2+H2O
2 mole of HCL=1 moles of CaCO3
0.005mole give 0.005/2 mole of CaCO3
0.0025 moles of cacO3
Mass of caCO3=0.0025*100
=0.25g
Thus, percentage =0.25/0.5
=0.5 *100%
=50%

thanks I appreciate. please review and tell me how sure you are. thanks in anticipation.

zhukafa:


thanks I appreciate. but how sure is your answer and workings.

I'm sure

Dr_Bode:
I'm sure

thanks man

Well..I just saw a mistake there @odilop. @Dr_bode...how did u get d no of moles of HCl there?

FunmbiLayo: Well..I just saw a mistake there @odilop. @Dr_bode...how did u get d no of moles of HCl there?

Which one exactly? Frm eqn 1 or eqn 2?

Yap Dr bode was correct I did a mistake.

Dr_Bode:
Which one exactly? Frm eqn 1 or eqn 2?

the mole is correct.

Odilop: Yap Dr bode was correct I did a mistake.the mole is correct.

thanks all, I appreciate. I also have some more questions for you friends to help me out with. I will post them later. once more, thanks.

zhukafa:

thanks all, I appreciate. I also have some more questions for you friends to help me out with. I will post them later. once more, thanks.

welcome bro.more question...

My Brothers and friends, thanks for your previous assistance. Still help with this one. thanks.

1) Mercury -197 is used for kidney scans and has a half-life of 3 days. If the amount of mercury-197 needed for a study is 1.0 gram and the time allowed for shipment is 15 days, how much mercury-197 will need to be ordered?

2) The half-life of strontium-90 is 25 years. How much strontium-90 will remain after 100 years if the initial amount is 4.0 g?

3) If the half-life of uranium-232 is 70 years, how many half-lives will it take for 10 g of it to be reduced to 1.25 g?

help out please.

still waiting

Good morning friends