Help please! Chem 1/2 solubility/concentration question

[Andiio]

The teacher I had last semester didn't even teach us anything.. she was really bad and sighhh kept getting everything wrong.
Could you guys please help me with these 2 questions? Please show full working!

1. A particular cordial contains 0.3 mg L^-1 of the synthetic food dye tartrazine, which causes adverse reactions in some people. What is its concentration in %(w/v)?

2. A certain brand of oven cleaner contains 4.33% (w/w) sodium hydroxide, NaOH. What is the concentration of the NaOH in mg/g?


Thanks in advance!!

[pooshwaltzer]

1. 0.3% w/v

2. 43.3mg/g

[Andiio]

Working out/explanation for q2? I know these two questions are really easy but my teacher hasn't taught us anything

[pooshwaltzer]

2. 1000mg in 1g ... 0.0433*1000 = 43.3mg

[qshyrn]

%(w/v) is weight(grams) in 100mL
0.3mg in 1L --> 0.3/10 mg in 100mL  -->0.03*10^-3 g in 100ml  =0.00003g in 100ml so 3*10^-5  %(w/v)

%w/w is grams per 100 grams    4.33 g/100g =4.33/100 (g/g)  = 4.33*10^-2 (g/g )= 4.33*10^-2*10^3 (mg/g) =43.3 mg/g

[Andiio]

Thank you all!!!