For a chemistry experiment Laura needs 300 ml of a 15% sulphuric acid solution. The Science Department has quantities of 5% acid solution and 20% acid solution. What volume of each solution is required to mix together to get her required concentration? Use a complete algebraic solution, including a proper verification.

100 ml of 5% solution

200 ml of  20% solution

Step-by-step explanation:

x = amount of 5% solution

y = amount of 20% solution

System of equations:

x + y = 300

.05x + .20y = 300(.15)

Solve by substitution:  let y = 300 - x

.05x + .2(300-x) = 300(.15)

.05x + 60 - .20x = 45

-.15x = -15

x = 100, therefore y = 200

step-by-step explanation:

the original amount doesn't ''re just looking for the time it takes for 1/2 of the substance to we have

(1/2) =)     take the ln   of both sides

ln (1/2)   = )   and we can write

ln(1/2) = ) lne     and lne   = 1     so we have

ln(1/2) = -.1092t     divide both sides by -.1092

t = ln(1/2)/-.1092 = about 6.347 days = about 6.3 days (rounded)

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step-by-step explanatio89