Help needed based on the Mole (1 Viewer)

[Pepperpie]

Hi I have a couple of questions that I need help with that's got to do with mole

1. How many moles of calcium hydroxide are needed to make 2.000L of 0.01M solution? What mass of calcium hydroxide would be required?

2. What volume of 0.05M potassium sulfate contain 50.0g of potassium sulfate?

3. What is the concentration pf magnesium sulfate if 20.0g of crystals (MgSO4 . 7H2O) are dissolved in 500mL of solution?

4. What is the mass of hydrogen chloride in 2.50L of 10.5M hydrochloric acid solution?

5. What mass of iron(II) is present in 25.00mL of 0.10M solution?

 

[Pepperpie]

Thanks if you can help, I was given these questions by the teacher and I have no clue how to do them cause I was away from school

 

[Omed62]

Hey lol,

I will try my best to make you understand them much better that you will never forget!

lets begin

Q1. First find the moles of CaOH using the equ: c= n/v, so n= 0.01x2= 0.02 moles, now you can work out the mass by using this mole equation, m= nx Mm, so m= 0.02 x ( molar mass using the periodic table, lol)= ?

Q2. v= n/Mv, so n= m/Mn, so n= 10.5/135.17= ?, now using the equ: v= n/Mv.

Q3. Find the moles of magnesium sulfate using the mass given, then use c= n/v.

Q4. Find the moles of HCL using the equation c= n/v, then work out the moles of hydrogen chloride ( same as the moles of HCL) then use the mole equ: m= n (moles) x Mm(molar mass).

Q5. Similar to the above, same way but here first make sure to change the 25.00ml to litres first before you start calculating. so you do it like this;

n= c x v, so n= 0.10x 0.025= 0.0025moles, now using the equation m= n x Mm, so m= 0.0025 x Mm(molar mass of iron(II) = ?

Good luck, I know sometimes chemistry can get hard but if you work hard and finding a good tutor from the start of year 11 could help you, lol.

 

[Omed62]

let me know if you need a tutor, I just started tutoring some of my friends, they start to improve dramatically.

Do they working and you can post your answer here, I can check it for you!

With, chemistry try to spend time sometimes to go over you notes, then do past papers alot to learn the concepts well enough, so you don't lose a single mark in the exam ever!

Good luck

 

[Pepperpie]

Hey thanks for the explanations but for the first q I don't really understand where the 0.01 came from and where do you tutor?

 

[nerdasdasd]

Hey thanks for the explanations but for the first q I don't really understand where the 0.01 came from and where do you tutor?

0.01 is the amount of moles.

so n= 0.01 (concentration) x 2 (number of litres)= 0.02 moles

 

[Omed62]

Hey thanks for the explanations but for the first q I don't really understand where the 0.01 came from and where do you tutor?

Lol, based on what your question says!
concentration (c)= 0.01M
volume (v) in litres= 2L

so 0.01 is the concentration, see in the equation: c= n/v, you can rearrange this to get, n= c x v, now n= 0.01 x 2(volume in litres)= 0.02 moles

I tutor in blacktown liberray or parramatta liberray sometimes.

 

[Omed62]

0.01 is the amount of moles.

so n= 0.01 (concentration) x 2 (number of litres)= 0.02 moles

Good job, lol

what did you get for chemistry in HSC

 

[nerdasdasd]

Good job, lol

what did you get for chemistry in HSC

lol, I know this, just didn't elaborate so much. Everyone doing chem should know that c = n/v and n = cv. I got a b5.

 

[Pepperpie]

Thank you so much!! This has helped me a lot!! wow blacktown and paramatta is pretty far for me to travel aha. One more question what does Mv stand for? I don't think I've learnt that yet aha thanks heaps

 

[nerdasdasd]

Thank you so much!! This has helped me a lot!! wow blacktown and paramatta is pretty far for me to travel aha. One more question what does Mv stand for? I don't think I've learnt that yet aha thanks heaps

MV stands for molarity (also known as concentration) x volume. This is used to find the moles of a solution.

 

[Omed62]

Thank you so much!! This has helped me a lot!! wow blacktown and paramatta is pretty far for me to travel aha. One more question what does Mv stand for? I don't think I've learnt that yet aha thanks heaps

Mv stands for Molar volume, check the back of the period table at the top.

Know these equation well enough because you will use them in the HSC!!

Good luck, I am willing to help anyone here! becasue once I was in your stuition look for help all the time and one day I start worked hard, got 100% across the year in chemistry in year 11. So basically chemistry is just second nature to me.

good luck once again

 

[Omed62]

MV stands for mass x volume. This is used to find the moles of a solution.

lol,

I think he means Mv from the equation n= v/Mv, so Mv is the molar volume, not mass x volume.

 

[Omed62]

MV stands for molarity (also known as concentration) x volume. This is used to find the moles of a solution.

dude, you don't know your equations! sorry but your trying to confuse OP!

I am trying to make thing simple for him, your just ruining it.

M stands for molarity ( meaing concentration of a solution), not Mv.

n (moles)= c(morality M) x v (volume of a solution) is used to find the moles of a solution

if you think I am wrong prove this one, hahah

 

[nerdasdasd]

Sorry guys, my chemistry went down the drain since the exam. I crammed it, and just forgot it all after... I shall stop.

 

[Omed62]

Sorry guys, my chemistry went down the drain since the exam. I crammed it, and just forgot it all after... I shall stop.

Lol, did I say something wrong to you!

 

[nerdasdasd]

Lol, did I say something wrong to you!

I'm not competent anymore in chem... so yeah, I'm not really helping...

 

[Pepperpie]

I also need help with;
what is the concentration of;
1) lead ions in a 0.02M solution of lead nitrate
2) iron(III) ions in a solution of magnesium iodide where [NO3 -] =0.45M (- is minus 1)

 

[Omed62]

I also need help with;
what is the concentration of;
1) lead ions in a 0.02M solution of lead nitrate
2) iron(III) ions in a solution of magnesium iodide where [NO3 -] =0.45M (- is minus 1)

Where did you get this questions from!

 

[Pepperpie]

lol, I am so busy studying? sorry I guess I can't help you anymore! I am busy doing Umat and 4u maths!

jokes! haha

I am back!

1. The question is wrong, isn't it? Think about it, how can you find the concentration if your not given moles(n).
2. same as above

Where did you get this questions from!

I got the questions from a booklet. I'm planning to do UMAT next year lol but I didn't buy the preparation packages yet btw good luck with UMAT!