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VCE Stuff => VCE Science => VCE Mathematics/Science/Technology => VCE Subjects + Help => VCE Chemistry => Topic started by: 2happy on November 05, 2007, 10:48:12 pm

Title: Chem Qstns
Post by: 2happy on November 05, 2007, 10:48:12 pm

A solution is prepared by dissolving 25g of NaCL into a glass containing 250ml of water. Given that the density of water is 1g mL^-1, the mass of NaCl in 100g of solution is?

Title: Re: Chem Qstns
Post by: ninwa on November 05, 2007, 10:58:06 pm

Quote from: "2happy"

A solution is prepared by dissolving 25g of NaCL into a glass containing 250ml of water. Given that the density of water is 1g mL^-1, the mass of NaCl in 100g of solution is?

 :? 10g?

seeing as 100g of solution = 100 mL?

that doesn't look right tho ... it's too simple an explanation ... where are the chem whizzes :P

Title: Re: Chem Qstns
Post by: melanie.dee on November 05, 2007, 11:02:55 pm

Quote from: "2happy"

A solution is prepared by dissolving 25g of NaCL into a glass containing 250ml of water. Given that the density of water is 1g mL^-1, the mass of NaCl in 100g of solution is?

250mL (250g) of water + 25g of NaCL = 275g of NaCl solution

25 x 100/275 = 9.09g

i think :?:

i think its a trick question, trying to fool you into thinking its just 10g

Title: Re: Chem Qstns
Post by: BA22 on November 05, 2007, 11:04:08 pm

Quote from: "melanie.dee"

Quote from: "2happy"

A solution is prepared by dissolving 25g of NaCL into a glass containing 250ml of water. Given that the density of water is 1g mL^-1, the mass of NaCl in 100g of solution is?

250mL (250g) of water + 25g of NaCL = 275g of NaCl solution

25 x 100/275 = 9.09g

i think :?:

yep

Title: Chem Qstns
Post by: 2happy on November 05, 2007, 11:16:19 pm

know where i can find unit 2 summaries?

Title: Re: Chem Qstns
Post by: 2happy on November 05, 2007, 11:17:54 pm

Quote from: "melanie.dee"

Quote from: "2happy"

A solution is prepared by dissolving 25g of NaCL into a glass containing 250ml of water. Given that the density of water is 1g mL^-1, the mass of NaCl in 100g of solution is?

250mL (250g) of water + 25g of NaCL = 275g of NaCl solution

25 x 100/275 = 9.09g

i think :?:

i think its a trick question, trying to fool you into thinking its just 10g

why is it 100/275?

Title: Re: Chem Qstns
Post by: melanie.dee on November 05, 2007, 11:27:05 pm

Quote from: "2happy"

Quote from: "melanie.dee"

Quote from: "2happy"

A solution is prepared by dissolving 25g of NaCL into a glass containing 250ml of water. Given that the density of water is 1g mL^-1, the mass of NaCl in 100g of solution is?

250mL (250g) of water + 25g of NaCL = 275g of NaCl solution

25 x 100/275 = 9.09g

i think :?:

i think its a trick question, trying to fool you into thinking its just 10g

why is it 100/275?

um well you want the amount thats in 100g and you have the amount thats in 275g. sooo you times is by 100/275

or if it makes more sense to you..

divide it by 275 to find the amount in 1g. and then times that by 100 to find the amount in 100g.