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VCE Stuff => VCE Science => VCE Mathematics/Science/Technology => VCE Subjects + Help => VCE Chemistry => Topic started by: sam0001 on May 22, 2012, 10:40:50 pm

Title: Hey, help?
Post by: sam0001 on May 22, 2012, 10:40:50 pm: 1.05 grams of peach was weighed and placed Ina beaker, and 50 ml of water was added. Th solution was transferred to a 1 L volumetric flask and the solution made to the distillation mark. A further solution was made by taking a 10 ml aliquot and diluting it to 100 ml. 20 ml hcl was then added to release the Cu ions. Th concentration of the final diluted solution 10 micrograms peer milliliter. What is the concentration in the original sample as g per kg.

Suggestions?
:)
Title: Re: Hey, help?
Post by: Mao on May 23, 2012, 01:35:25 am: In the final solution: $10 \mu g / mL = 1200 \mu g / 120 mL = 1.2 mg / 120 mL$

In the 10 mL aliquot: $1.2 mg / 120 mL \implies 1.2 mg / 10 mL$

In the 1L V.Flask: $1.2 mg / 10 mL \implies 120 mg / L = 0.12 g / L$

In the 50 mL of initial solution $0.12 g / L \implies 0.12 g / 50 mL$

In the peach: $0.12 g / 50 mL \implies 0.12 g / 1.05 g = 0.114 g / g = 114 g / kg$

That is a crap ton of copper. Did I make a stupid mistake somewhere?
Title: Re: Hey, help?
Post by: sam0001 on May 23, 2012, 07:51:53 pm: I think I made some errors in my typing out. Tanks though! Was confused as to whether I should include the hcl or not.