*bwah* Help with ppm? (1 Viewer)

[LuthienAdrianna]

This is a multiple choice question from the 2005 Chemistry Catholic Trial Paper:

Oysters provide a rich source of zinc, an essential trace element in our diet. The minimum recommended intake for an adult is 12mg per day.

If a sample of oysters was found by AAS to contain an average of 200ppm of zinc per oyster, how many oysters would an adult have to eat to reach the minimum recommended daily intake?

A) 0.2
B) 1.7
C) 6
D) 12

I know the answer, but for the life of me cannot figure out why. ><

Much appreciated, Andriana.

 

[Riviet]

I think it's A because:

no. of oysters = 12/200
=0.06

The nearest answer to this is A and correct me anyone if I'm actually wrong.

 

[Forbidden.]

I bet this is in the HSC Chemistry course ...

How many ppm is there in each gram ?
Just for useful reference ...

 

[pLuvia]

1mg in 1 kilogram = 1ppm

 

[Forbidden.]

1mg in 1 kilogram = 1ppm

So if:

I bought 1 Litre of bottled water and there happens to be 2mg of Potassium found, would the answer be 2ppm ?

There is a tank of 50 Litres of Helium and there happens to be 5mg of Argon found would it be 5ppm or 0.1ppm ?

I'm a little confused with the ppm as I like a good headstart ..

 

[tennille]

It would be 0.1 ppm. 5mg/50L is equivalent to 1mg/10L. Therefore, 0.1mg/L = 0.1 ppm.

 

[Forbidden.]

It would be 0.1 ppm. 5mg/50L is equivalent to 1mg/10L. Therefore, 0.1mg/L = 0.1 ppm.

Thanks, could you tell me how to get Premium Membership with a debit card ?

 

[LuthienAdrianna]

I think it's A because:

no. of oysters = 12/200
=0.06

The nearest answer to this is A and correct me anyone if I'm actually wrong.

The answer is actually C) 6. ><

 

[tennille]

Thanks, could you tell me how to get Premium Membership with a debit card ?

I think you can only use paypal or a credit card. However, if you go to your control panel and click on "subscriptions", all the information should be there.

 

[LuthienAdrianna]

... Anyone else want to have a crack at it?

 

[rama_v]

The question is badly written. There was a big debate about it last year. You can view what ppl had to say about it here:

Long story short, forget about the question.

http://community.boredofstudies.org/17/chemistry/81124/cssa-results/3.html?highlight=oyster

Link edited. Sorry, should have checked them.

 

[Forbidden.]

... Anyone else want to have a crack at it?

Let's cover basics FTW ..

1. How many moles in 32g of oxygen ?
2. Is Silver Chloride (AgCl) soluble ?
3. Is photosynthesis an exothermic reaction or endothermic reaction ?
4. What is the name of this compound - C₈H₁₈ ?

The question is badly written. There was a big debate about it last year. You can view what ppl had to say about it here:

Long story short, forget about the question.

http://community.boredofstudies.org/...ghlight=oyster
http://community.boredofstudies.org/...ghlight=oyster

Those two links direct me to the main BOS forums ...

 

[Riviet]

Solution to oyster question

about the oyster question... it is quite simple to find out the answer.

You have to know that 100ppm = 1mg. The question then says that the sample contains 200ppm, so if 100ppm - 1mg, then 200ppm = 2mg. and the recommended dietary intake is 12mg. So 12/2 gives you 6 oysters.

I guess it was the bit in red that caused most of the controversy.

 

[LuthienAdrianna]

Let's cover basics FTW ..

1. How many moles in 32g of oxygen ?
2. Is Silver Chloride (AgCl) soluble ?
3. Is photosynthesis an exothermic reaction or endothermic reaction ?
4. What is the name of this compound - C₈H₁₈ ?



Those two links direct me to the main BOS forums ...

Okay...

1) 2 moles
2) Yes? :S
3) Endothermic
4) Octane

 

[Riviet]

Silver happens to be one of the exceptions with the solubility rule about halides. In other words, silver chloride is insoluble.

 

[LuthienAdrianna]

Ah. Ok. >< Does this solubility stuff get revisited in CM/M? I remember doing this for the prelim course, but since we haven't finished this syllabus yet...

 

[Riviet]

Ah. Ok. >< Does this solubility stuff get revisited in CM/M? I remember doing this for the prelim course, but since we haven't finished this syllabus yet...

It does with the identification of ions section in CMM. Also knowing the solubility rules may become handy in an exam...

 

[Forbidden.]

Okay...

1) 2 moles
2) Yes? :S
3) Endothermic
4) Octane

Ha ha ! Silver Chloride is not soluble !

Silver happens to be one of the exceptions with the solubility rule about halides. In other words, silver chloride is insoluble.

That is my point

Good there both of you, at least you remembered something from the preliminary year ... *sigh* ... Prelim Yearly exams then comes our HSC Course in Term 4 ...