# Help with a chemistry question!

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Mudas

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#1

Its located on the OCR sample paper for 2015 if anyone is wondering. It states:

A student mixes 100cm3 of 0.200 mol dm-3 NaCl (Aq) with 100cm3 of 0.200 mol dm-3 (Na2)C(O3).

What is the total concentration of Na+ ions in the mixture formed?

Any clue how you do this?

A student mixes 100cm3 of 0.200 mol dm-3 NaCl (Aq) with 100cm3 of 0.200 mol dm-3 (Na2)C(O3).

What is the total concentration of Na+ ions in the mixture formed?

Any clue how you do this?

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alow

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#2

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#2

(Original post by

Its located on the OCR sample paper for 2015 if anyone is wondering. It states:

A student mixes 100cm3 of 0.200 mol dm-3 NaCl (Aq) with 100cm3 of 0.200 mol dm-3 (Na2)C(O3).

What is the total concentration of Na+ ions in the mixture formed?

Any clue how you do this?

**HarrisonGCSE**)Its located on the OCR sample paper for 2015 if anyone is wondering. It states:

A student mixes 100cm3 of 0.200 mol dm-3 NaCl (Aq) with 100cm3 of 0.200 mol dm-3 (Na2)C(O3).

What is the total concentration of Na+ ions in the mixture formed?

Any clue how you do this?

^{+}in each sample.

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TheConfusedMedic

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#3

Mudas

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#4

Figured it out!

0.1 x 0.2 = 0.02 moles of NaCl. Therefore, there are 0.02 moles of Na+ in the NaCl

0.1 x 0.2 = 0.02 moles of Na2C03. Therefore, there are 0.02 moles of Na2 in the Na2CO3 meaning there are 0.04 moles of Na+ in Na2CO3.

0.02 + 0.04 = 0.06 moles

The total volume is 200cm3.

0.06/ 0.02dm3 = 0.3mol/dm3

0.1 x 0.2 = 0.02 moles of NaCl. Therefore, there are 0.02 moles of Na+ in the NaCl

0.1 x 0.2 = 0.02 moles of Na2C03. Therefore, there are 0.02 moles of Na2 in the Na2CO3 meaning there are 0.04 moles of Na+ in Na2CO3.

0.02 + 0.04 = 0.06 moles

The total volume is 200cm3.

0.06/ 0.02dm3 = 0.3mol/dm3

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TheConfusedMedic

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#5

(Original post by

Figured it out!

0.1 x 0.2 = 0.02 moles of NaCl. Therefore, there are 0.02 moles of Na+ in the NaCl

0.1 x 0.2 = 0.02 moles of Na2C03. Therefore, there are 0.02 moles of Na2 in the Na2CO3 meaning there are 0.04 moles of Na+ in Na2CO3.

0.02 + 0.04 = 0.06 moles

The total volume is 200cm3.

0.06/ 0.02dm3 = 0.3mol/dm3

**HarrisonGCSE**)Figured it out!

0.1 x 0.2 = 0.02 moles of NaCl. Therefore, there are 0.02 moles of Na+ in the NaCl

0.1 x 0.2 = 0.02 moles of Na2C03. Therefore, there are 0.02 moles of Na2 in the Na2CO3 meaning there are 0.04 moles of Na+ in Na2CO3.

0.02 + 0.04 = 0.06 moles

The total volume is 200cm3.

0.06/ 0.02dm3 = 0.3mol/dm3

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molly221

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#6

Rchilton

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#7

(Original post by

Can anyone help me with this question? Thanks

**molly221**)Can anyone help me with this question? Thanks

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coconut64

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#8

**HarrisonGCSE**)

Figured it out!

0.1 x 0.2 = 0.02 moles of NaCl. Therefore, there are 0.02 moles of Na+ in the NaCl

0.1 x 0.2 = 0.02 moles of Na2C03. Therefore, there are 0.02 moles of Na2 in the Na2CO3 meaning there are 0.04 moles of Na+ in Na2CO3.

0.02 + 0.04 = 0.06 moles

The total volume is 200cm3.

0.06/ 0.02dm3 = 0.3mol/dm3

1) Why is the mole of Na+ ions in NaCl 0.02mol? Isn't that the number of moles for NaCl?

2) I have also worked out that Na2CO3 is 0.02 moles but again I don't get why Na+ would also be 0.02 mol

3) I understand that the total volume is 200 but why did you get 0.02dm3 from? That's not the volume though...

Thanks in advance!

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coconut64

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#9

(Original post by

Thanks! I was stupid and when I saw there was 0.02 moles NaCl, I divided it by 2 to get 0.01 moles Na+ () and used the same technique for the other solution

**surina16**)Thanks! I was stupid and when I saw there was 0.02 moles NaCl, I divided it by 2 to get 0.01 moles Na+ () and used the same technique for the other solution

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Rchilton

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#10

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#10

(Original post by

Hi, could you please explain to me how you solved this question? I still don't get it. Why is the mole of Na+ ions the same as the mole of NaCl? Thank you.

**coconut64**)Hi, could you please explain to me how you solved this question? I still don't get it. Why is the mole of Na+ ions the same as the mole of NaCl? Thank you.

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TheConfusedMedic

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#11

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#11

**coconut64**)

Hi, could you please explain to me how you solved this question? I still don't get it. Why is the mole of Na+ ions the same as the mole of NaCl? Thank you.

Therefore, if you have 0.02 moles of NaCl, you have 0.02 moles Na+ and 0.02 moles Cl-

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coconut64

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#12

(Original post by

If you have 1 mole of NaCl, it means that you have 1 mole of Na+ and 1 mole of Cl-, bonded together.

Therefore, if you have 0.02 moles of NaCl, you have 0.02 moles Na+ and 0.02 moles Cl-

**surina16**)If you have 1 mole of NaCl, it means that you have 1 mole of Na+ and 1 mole of Cl-, bonded together.

Therefore, if you have 0.02 moles of NaCl, you have 0.02 moles Na+ and 0.02 moles Cl-

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Rchilton

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#13

(Original post by

3) I understand that the total volume is 200 but why did you get 0.02dm3 from? That's not the volume though...

Thanks in advance!

**coconut64**)3) I understand that the total volume is 200 but why did you get 0.02dm3 from? That's not the volume though...

Thanks in advance!

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#14

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#14

(Original post by

I think it's a typo and meant to be 0.2dm3. Which you get if you convert 200cm3 in to dm3. (10 cm in a dm, but as it's a volume it's 10^3 = 1000)

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**Rchilton**)I think it's a typo and meant to be 0.2dm3. Which you get if you convert 200cm3 in to dm3. (10 cm in a dm, but as it's a volume it's 10^3 = 1000)

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#15

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#15

(Original post by

Oh okay. So if the mole of Na2Co3 is 0.4 mol, the mole of Na2 would be 0.2mol?

**coconut64**)Oh okay. So if the mole of Na2Co3 is 0.4 mol, the mole of Na2 would be 0.2mol?

*think*you would have 0.4 mol Na2 which therefore means you would have 0.8 mol Na+

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not 100% sure, but it seems to make sense logically

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#16

(Original post by

No I

**surina16**)No I

*think*you would have 0.4 mol Na2 which therefore means you would have 0.2 mol Na
Spoiler:

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not 100% sure, but it seems to make sense logically

Really? But the OP mentioned that '0.1 x 0.2 = 0.02 moles of Na2C03. Therefore, there are 0.02 moles of Na2 in the Na2CO3 meaning there are 0.04 moles of Na+ in Na2CO3. ' So 0.02 mole for Na2. For all Na+ion, it will be 0.02*2. So if the mole of Na2CO3 is 0.4mole. Na2 ions will be 0.4 mole. All Na ions will be 0.8 right?

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#17

(Original post by

Really? But the OP mentioned that '0.1 x 0.2 = 0.02 moles of Na2C03. Therefore, there are 0.02 moles of Na2 in the Na2CO3 meaning there are 0.04 moles of Na+ in Na2CO3. ' So 0.02 mole for Na2. For all Na+ion, it will be 0.02*2. So if the mole of Na2CO3 is 0.4mole. Na2 ions will be 0.4 mole. All Na ions will be 0.8 right?

**coconut64**)Really? But the OP mentioned that '0.1 x 0.2 = 0.02 moles of Na2C03. Therefore, there are 0.02 moles of Na2 in the Na2CO3 meaning there are 0.04 moles of Na+ in Na2CO3. ' So 0.02 mole for Na2. For all Na+ion, it will be 0.02*2. So if the mole of Na2CO3 is 0.4mole. Na2 ions will be 0.4 mole. All Na ions will be 0.8 right?

Sorry for the confusion

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#18

(Original post by

Oh yeah of course aha I meant to multiply by 2, not divide

Sorry for the confusion

**surina16**)Oh yeah of course aha I meant to multiply by 2, not divide

Sorry for the confusion

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kekeAqueil

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#19

plz can anyone help me I'm stuck.. Thanks

1.what is the molar its of a solution made by dissolving 49g of H2SO4, in water and diluting with water to 200ml total?

2. some compound has 14.3% C, 2.4%H, and 33.31% N,and has molecular mass of 126. what is the molecular formula of that compound.

1.what is the molar its of a solution made by dissolving 49g of H2SO4, in water and diluting with water to 200ml total?

2. some compound has 14.3% C, 2.4%H, and 33.31% N,and has molecular mass of 126. what is the molecular formula of that compound.

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Terminator2766

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#20

It is 0.01 x 0.2as when figuring out moles you need to convert the 100cm3 to dm3 and to do that you need to divide by 1000.if you do that you get 0.002 0.004 = 0.006and then 0.006/0.02 = 0.3(0.06 / 0.02 = 3)

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