Mixing solutions

		Quandaries and Queries
	Name: Margaret Who is asking: Student Level: Secondary Question: In a chemistry laboratory the concentration of one solution is 10% hydrocholoric acid (HCl) and that of a second soulution is 60% HCl. How many mL of each should be mixed to obtain 50 mL of a 30% HCl solution?? Any help is appreciated. Thanks ahead of time, Margaret
	Hi Margaret, If the object is to have 50 ml of liquid, 30% of which is HCl then you need 50 x ³⁰/₁₀₀ = 15 ml of HCl. If the 50 ml are obtained using k ml of the first solution then you also need 50 - k ml of the second solution. The first solution is 10% HCl and hence k ml of the first solution gives k x ¹⁰/₁₀₀ ml of HCl. The second solution is 60% HCl and hence k ml of the first solution gives (50 - k) x ⁶⁰/₁₀₀ ml of HCl. Thus k x ¹⁰/₁₀₀ + (50 - k) x ⁶⁰/₁₀₀ = 15 Penny
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