White Board Review Practicing with Concentration Expressions •Molarity •Percent •ppm
Jan 19, 2016
White Board Review
Practicing with Concentration Expressions
•Molarity•Percent•ppm
Determine the molarity of 250 mL of solution containing 35 g of NaOH.
mol soluteM =
L solution
What you must remember: molarity = moles of solute per liter of solution
1 mol NaOH
40.0 g NaOH
=
35 g NaOH
0.250 Liters
= 3.5 M NaOH
Practicing with Concentrations Molarity
What volume of a 2.0 M solution will provide 18 g of NaOH?
1.0 L
2.0 mol NaOH
What you must remember: moles solute ÷ molarity = L volume
1 mol NaOH
40.0 g NaOH
=18 g NaOH 0.45 mol NaOH
= 0.23 L0.45 mol NaOH
or 230 mL of solution
First find moles:
Next, divide moles by molarity:
Practicing with Concentrations Molarity
What mass of NaOH is needed to make 4.0 liters of a 0.75 M solution?
40.0 g NaOH
1 mol NaOH
What you must remember: L volume X molarity = moles solute
0.75 mol NaOH
L solution
=4.0 L solution 3.0 mol NaOH
=120 g NaOH3.0 mol NaOH
First find moles solute:
Next, multiply moles by molar mass:
Practicing with Concentrations Molarity
Determine the molarity of 850 mL of solution containing 95 g of KCl.
mol soluteM =
L solution
What you must remember: molarity = moles of solute per liter of solution
1 mol KCl
74.6 g KCl
=
95 g KCl
0.850 Liters
= 1.5 M KCl
Practicing with Concentrations Molarity
What volume of a 3.8 M solution will provide 120 g of LiF?
1.0 L
3.8 mol LiF
What you must remember: moles solute ÷ molarity = L volume
1 mol LiF
25.9 g LiF
=120 g LiF 4.63 mol LiF
= 1.2 L4.63 mol LiF
First find moles:
Next, divide moles by molarity:
Practicing with Concentrations Molarity
Practicing with Concentrations Molarity
What mass of NaSCN is needed to make 550 mL of a 2.4 M solution?
81.1 g NaSCN
1 mol NaSCN
What you must remember: L volume X molarity = moles solute
2.4 mol NaSCN
L solution
=0.55L solution 1.32 mol NaSCN
=110 g NaSCN1.32 mol NaSCN
First find moles solute:
Next, multiply moles by molar mass:
Determine the % w/v of 25 mL of solution containing 3.0 g of CsOH.
mv
2g solute% = 10
mL solution
What you must remember: % w/v = g of solute per mL of solution X 100
= 3.0 g CsOH
25 mL
= 12 % w/v CsOH
Practicing with Concentrations Percent
x 102
What volume of a 6.2 % w/v solution will provide 32 g of KMnO4?
What you must remember: g solute ÷ % w/v = mL volume
Practicing with Concentrations Percent
4
solution
6.2 g KMnO
100 mL
= 520 mL KMnO4 solution
First interpret % w/v: Next, divide the g solute by the %:
32 g4
solution100 mL
6.2 g KMnO
Practicing with Concentrations
What mass of NaClO is needed to make 150 mL of a 4.9 % w/v solution?
What you must remember: % w/v = g/100mL and mL volume X % = g solute
solution
4.9 g NaClO
100 mL
= 7.4 g NaClOX
First interpret % w/v: Next, multiply by mL volume:
Percent
150 mL
Determine the % w/v of 960 mL of solution containing 37 g of KClO3.
mv
2g solute% = 10
mL solution
What you must remember: % w/v = g of solute per mL of solution X 100
= 37 g KClO3
960 mL
= 3.9 % w/v KClO3
Practicing with Concentrations Percent
x 102
What volume of a 0.55 % w/v solution will provide 2.5 g of KNO2?
What you must remember: g solute ÷ % w/v = mL volume
Practicing with Concentrations Percent
2
solution
0.55 g KNO
100 mL
= 450 mL KNO2 solution
First interpret % w/v: Next, divide the g solute by the %:
2.5 g2
solution100 mL
0.55 g KNO
Practicing with Concentrations
What mass of NaSO4 is needed to make 500. mL of a 1.0 % w/v solution?
What you must remember: % w/v = g/100mL and mL volume X % = g solute
4
solution
1.0 g NaSO
100 mL
= 5.0 g NaSO4X
First interpret % w/v: Next, multiply by mL volume:
Percent
500. mL
Calculate the concentration in ppm of 3250mL of solution containing 0.25 g of NiSeO3.
6g soluteppm = 10
mL solution
What you must remember: ppm = g of solute per mL of solution X 106
= 0.25 g NiSeO3
3250 mL
= 77 ppm NiSeO3
Practicing with Concentrations ppm
x 106
What volume of a 320 ppm solution will provide 0.75 g of K2Cr2O7?
What you must remember: ppm = mg/L and mg solute ÷ ppm = L volume
Practicing with Concentrations
2 2 7
solution
320 mg K Cr O
1 L
= 750 mg
First interpret ppm: Next, convert g to mg:
0.75 g 1000 mg
1 g
ppm
Finally, divide mg solute by ppm:
750 mg2 2 7
solution1 L
320 mg K Cr O
= 2.3 L
Practicing with Concentrations
What mass of MgSO3 is needed to make 100. mL of a 38 ppm solution?
What you must remember: ppm = mg/L and L volume X ppm = mg solute
3
solution
38 mg MgSO
1 L
= 3.8 mg MgSO3X
First interpret ppm: Next, multiply by L volume:
0.100 L
ppm
Calculate the concentration in ppm of 25,000mL of solution containing 1.0 g of KF.
6g soluteppm = 10
mL solution
What you must remember: ppm = g of solute per mL of solution X 106
= 1.0 g KF
25,000 mL
= 40. ppm KF
Practicing with Concentrations ppm
x 106
What volume of a 5.0 ppm solution will provide 1.0 g of NaCN?
What you must remember: ppm = mg/L and mg solute ÷ ppm = L volume
Practicing with Concentrations
solution
5.0 mg NaCN
1 L
= 1000 mg
First interpret ppm: Next, convert g to mg:
1.0 g 1000 mg
1 g
ppm
Finally, divide mg solute by ppm:
1000 mgsolution1 L
5.0 mg NaCN
= 2.0 x 102 L
Practicing with Concentrations
What mass of FePO4 is needed to make 500. mL of a 120 ppm solution? What you must remember:
ppm = mg/L and L volume X ppm = mg solute
4
solution
120 mg FePO
1 L
= 60. mg FePO4X
First interpret ppm: Next, multiply by L volume:
0.500 L
ppm