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2 weeks ago
#81

The KOH is diluted as 40cm3 is added so you need to find the new concentration if that makes sense
(Original post by lois_____)
Anyone know how to get part a) the k+ Conc
Last edited by _nim1; 2 weeks ago
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2 weeks ago
#82
Thank you!! Why are you putting 20/60 tho ?
(Original post by _nim1)

The KOH is diluted as 40cm3 is added so you need to find the new concentration if that makes sense
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2 weeks ago
#83
Aw I see now tyty
(Original post by lois_____)
Thank you!! Why are you putting 20/60 tho ?
1
2 weeks ago
#84
20cm3 of KOH divided by the new total volume of 60cm3 then multiply that by the concentration. That’s how you find the concentration of solutions that are diluted : )
(Original post by lois_____)
Thank you!! Why are you putting 20/60 tho ?
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2 weeks ago
#85
For the same question how do you find the H+ conc?
(Original post by _nim1)
20cm3 of KOH divided by the new total volume of 60cm3 then multiply that by the concentration. That’s how you find the concentration of solutions that are diluted : )
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2 weeks ago
#86
Find the ph using ph= pka - log[acid]/[salt]
Then use the equation ph= -log[H+] just rearranging it
(Original post by Mhussain01)
For the same question how do you find the H+ conc?
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2 weeks ago
#87
Does anyone have the answers to yesterday's scholar session?
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2 weeks ago
#88
(Original post by A_Ch)
Does anyone have the answers to yesterday's scholar session?
SCHOLARuk are you able to help?
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2 weeks ago
#89
Anyone know how to do q4 ?
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2 weeks ago
#90
thank you so much x
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2 weeks ago
#91
how did you get 0.66 for the concentration of salt?
(Original post by _nim1)
Find the ph using ph= pka - log[acid]/[salt]
Then use the equation ph= -log[H+] just rearranging it
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2 weeks ago
#92
can anyone help me with these?

5. When one mole of phosphorus pentachloride was heated to 523K in a closed vessel, 50% dissociated as shown
PCl5(g) -> PCl3(g) + Cl2(g)
How many moles of gas were present in the equilibrium mixture?
A 0·5 B 1·0 C 1·5 D 2·0

7. Which of the following 0.01 mol l−1 aqueous solutions has the highest pH value?
A Sodium fluoride
B Sodium benzoate
C Sodium propanoate
D Sodium methanoate

10. Which of the following reactions would show the greatest decrease in entropy?
A H2(g) + F2(g) → 2HF(g)
B KNO3(s) → KNO2(s) + 1/2 O2(g)
C CO3^2−(aq) + 2H+(aq) → H2O(l) + CO2(g)
D CO3^2−(aq) + CO2(g) + H2O(l) → 2HCO^3−(aq)

20. Which of the following compounds would liberate one mole of hydrogen gas if one mole of it reacts with two moles of sodium?
A C2H5OH
B HOCH2CH2OH
C CH3COOH
D CH3CHO
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2 weeks ago
#93
For question 20, I think the answer is B because the reaction between a metal and an alcohol is an elimination reaction which removes the one hydrogen atom to make an alkene and if there are 2 moles of sodium then you would be looking for the molecule with 2 hydroxyl functional groups. Thats what I would do.
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2 weeks ago
#94
Can I get help on these questions please.
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2 weeks ago
#95
1
2 weeks ago
#96
Thank you!!
(Original post by lois_____)
0
2 weeks ago
#97
The concentration of the salt is 0.333 from the answer to part a)
The concentration of the acid is 0.667, found by 40/60 multiplied by the concentration which is 1
(Original post by chic geek)
how did you get 0.66 for the concentration of salt?
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2 weeks ago
#98
I think for the 2nd one, to get the right chloride ion concentration you’d need a total volume of 100ml but you’ve already got 25ml there so 100-25 = 75ml so wld need to be diluted by 75ml of water. So 75ml is the answer I would think
(Original post by A_Ch)
Can I get help on these questions please.
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2 weeks ago
#99
Ligands attach through electron pairs

(Original post by A_Ch)
Can I get help on these questions please.
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2 weeks ago
#100
(Original post by lois_____)
I think for the 2nd one, to get the right chloride ion concentration you’d need a total volume of 100ml but you’ve already got 25ml there so 100-25 = 75ml so wld need to be diluted by 75ml of water. So 75ml is the answer I would think
0
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