Question

In: Chemistry

2pts) Given 750ml of a 6M Na2CO3 stock solution, how much do you need to make...

2pts) Given 750ml of a 6M Na2CO3 stock solution, how much do you need to make 350ml of a 20% Na2CO3 working solution? Show your calculations for full credit.

Expert Solution

Solution :-

20 % solution means 20 g Na2CO3 in 100 ml solution

therefore for 350 ml solution mass of Na2CO3 needed is calculated as

350 ml * 20 g /100 ml = 70.0 g Na2CO3

now lets calculate moles of the 70.0 g Na2CO3

moles = mass / molar mass

moles of Na2CO3 = 70.0 g / 105.9888 g per mol

= 0.6604 mol Na2CO3

now lets use this moles and molarity of the stock solution to calculate volume of the stock solution needed

molarity = moles / volume in liter

so

volume in liter = moles / molarity

volume in liter = 0.6604 mol / 6 mol per liter

volume in liter = 0.1101 L

convert liter to ml

(0.1101 L * 1000 ml)/ 1 L = 110.1 ml

so we need 110.1 ml of the 6 M stock solution to make 350 ml 20 % solution

take 110.1 ml of the stock solution and dilute it to total volume of 350 ml.

queen_honey_blossom answered 2 years ago

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