24 Questions
What is the mass of NaCl required to prepare 250 mL of a 0.92% (w/v) NaCl solution?
2.3 g
What is the concentration of a solution in parts per million if 0.0054 g of MgCl2 is dissolved in 2000 g of solvent?
2.7 ppm
What is the molarity of a solution made from 20.0 g of NaOH in 250 mL of solution?
0.50 M
What is the weight/volume percent concentration of a solution that contains 2.3 g of NaCl in 250 mL of solution?
0.92%
What is the unit of concentration that represents the number of moles of solute per liter of solution?
Molarity
What is the concentration of a solution that contains 0.92 g of NaCl in 100 mL of solution?
0.92% (w/v)
What is the equivalent weight of CaBr2?
99.945 g/mol
How is the concentration of a solution often expressed when it contains a very small concentration of solute?
Parts per Million
What is the normality of a 0.4 g/100 mL solution of CaBr2?
0.02 N
What is the weight/volume percent concentration of a solution that contains 20 g of solute in 100 mL of solution?
20% (w/v)
What is the purpose of a conversion factor in solution chemistry calculations?
To cancel units
How many milliequivalents of Ca2+ are present in 0.4 g of CaBr2?
4 mEq
What is the volume/volume percent concentration of a solution that contains 30 mL of solute in 100 mL of solution?
30% (v/v)
How many grams of NaCl are contained in 500 mL of a 0.92% (w/v) NaCl solution?
9.2 g
What is the concentration of a solution that contains 25 g of solute in 200 mL of solution?
12.5% (w/v)
How many milliequivalents of Ca2+ are present in 0.2 g of CaBr2?
2 mEq
What is the amount of each ion in 1 mole of solution that relates to its charge?
Equivalent
How many equivalents are present in 0.5 mol of PO43-?
1 Eq
What is the concentration unit used to express the amount of ions in body fluids?
Milliequivalents per liter
How many milliequivalents are there in 1 equivalent?
1000 mEq
What is the number of positive ions always equal to in a neutral solution?
Number of negative ions
How many moles of magnesium ion are in 0.4 L of blood with a magnesium level of 16.0 mEq/L?
0.016 mol
What is the amount of calcium ion in 0.4 g of CaBr2?
0.4/2 mEq
What is the type of electrolyte that ionizes completely in solution?
Strong electrolyte
Study Notes
Concentration Units
- A 0.92% (w/v) NaCl solution is equivalent to 0.92 g NaCl per 100 mL of solution.
- To find the mass of NaCl in 250 mL of solution, use the conversion factor: 0.92 g NaCl / 100 mL solution.
Parts Per Million (ppm)
- ppm = (mass of solute (g) x 10^6) / mass of solution (g)
- ppm = (volume of solute (mL) x 10^6) / volume of solution (mL)
- Example: 0.0054 g of MgCl2 in 2000 g of solvent.
Molarity (M)
- Molarity is the number of moles of solute per liter of solution.
- M = moles of solute (mol) / liter of solution (L)
- Example: 20.0 g of NaOH in 250 mL of solution.
Weight/Volume Percent Concentration (w/v)%
- w/v% = (mass of solute (g) / volume of solution (mL)) x 100%
- Example: 5 g of acetic acid in 100 mL of solution is 5% w/v.
Volume/Volume Percent Concentration (v/v)%
- v/v% = (volume of solute (mL) / volume of solution (mL)) x 100%
- Example: 70 mL of 2-propanol in 100 mL of solution is 70% v/v.
Electrolytes
- Strong electrolytes: ionize completely in solution (e.g., NaCl → Na+ + Cl-)
- Weak electrolytes: ionize partially in solution (e.g., CH3COOH → H+ + CH3COO-)
Equivalents (Eq)
- Equivalent (Eq) is a unit used to express the amount of each ion in solution.
- Amount of ion in solution is determined by equivalent (Eq), which relates to its charge.
Milliequivalents (mEq)
- 1 Eq = 1000 mEq
- Concentration of ions in the body is determined by mEq/L.
Solve a problem involving concentration units and conversion factors, given a 0.92% NaCl solution and 250 mL volume. Apply conversion factors to find the desired quantity of NaCl.
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