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March 30, 2017

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a.)How many moles of NaOH are required to prepare 2.00L od 0.380M solution? answer is 0.760 mole of NaOH (mole/l * 2.00L)
b.)What will be the molarity of a solution if 3.50 g of KOH are dissolved in water to make 150.0 mL of solution? answer is 0.52 M KOH (gKOH/molar mass KOH=mole KOH; M=mol KOH/L)
c.)What volume of (mL) of 0.400M solution can be prepared by dissolving 5.00g of KOH in water? answer is 300mL (gKOH/molar mass=mole KOH;mole KOH * Molarity of the solution 0.400M=L of solution *ml)
d.) Calculate the weight of HCl in 35.0mL of comcentrated HCl (12.00M) solution. my asnswer is 15 g HCl ( mL to L; L * M=mol; mole* molar mass= g)
pls check my answers.

  • chem - ,

    I believe a is right with b and c wrong.
    For d you appear to have rounded the answer to 15g; however, you ha e three significant figures is 35.0 and 4 s.f. in 12.00M, so don't throw a good digit away. You should have 3 s.f. in your answer.
    b. mols KOH = 3.5/56.1 = ?mols
    M = ?mols/0.150 = ? about 0.4M

    c. mols KOH = 5.00/56.1 = about 0.89
    M = mols/L or L = mols/M = 0.089/0.400M = about 0.22L
    My answers are close; you should redo them for a more accurate answer. Also I've not kept up with the s.f. in my answers since they are estimates.

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