Concentration, Volume, and Dillutions Molarity, Normality
What is the normality (N) of a 700 mL solution that contains 5 g of H2SO4 (gmw=98 g/mol, valence=2)?
0.146 N
Convert 0.9% NaCl to molarity.
0.15M
Determine the molarity of a solution of KOH that is contained in a Class A 1-L volumetric flask filled to the calibration mark. The content label reads 18 g KOH. The gmw of KOH=56.1 g/mol. Please select the single best answer
0.32 mol/L
What is the normality (N) of a 500 mL solution that contains 8 g of H2SO4 (gmw=98 g/mol, valence=2)?
0.326 N
If there are 25g of NaCl per liter of solution, what is the molarity of the solution?
0.43M
How would one prepare 3 mL of a 5% albumin working solution from a stock 30% albumin solution?
0.5 mL stock 30% albumin + 2.5 mL diluent
What is the normality (N) of a 250 mL solution that contains 6 g of NaOH (gmw=39.997 g/mol, valence=1)?
0.600 N
Convert 800 microliters to milliliters.
0.80 mL
Determine the molarity of a solution of HCl that is contained in a Class A 1-L volumetric flask filled to the calibration mark. The content label reads 32 g HCl. The gmw of HCl=36.46 g/mol.
0.88 mol/L
How would you CORRECTLY prepare 100 mL of 0.9% isotonic saline (NaCl: GMW = 58.45)?
0.9 grams in 100 mL distilled water
How many milliliters of a 5 M solution would be needed to make 250 mL of a 2 M solution?
100 mL
An aqueous 3.00 M KOH solution is prepared with a total volume of 0.650 L. The molecular weight of KOH is 56.1056 g/mol. What mass of KOH (in grams) is needed for the solution?
109.4 g
How many grams are needed to make 1 L of a 3 M solution of HCl (gmw=36.46 g/mol)?
109.4 g HCl/L
The absorbance of a 40.0 mg/dL blood urea nitrogen (BUN) standard is 0.758. The absorbance of the patient's serum specimen is 0.220. What is the patient's serum BUN concentration (to the nearest tenths)?
11.6
After experiencing extreme fatigue and polyuria, a patient's basic metabolic panel is analyzed in the laboratory. The result of the glucose is too high for the instrument to read. The laboratorian performs a dilution using 0.25 mL of patient sample to 750 µL of diluent. The result now reads 325 mg/dL. How should the techologist report this patient's glucose result?
1300 mg/dL
A 24-hour urine collection requires HCl as a preservative. The procedure manual states the required concentration of HCl in percent rather than in normality. The laboratory only has 4N HCl available. What is the percent concentration? (HCl has a positive valence of 1)
14.6%
After experiencing extreme jaundice, abdominal pain, and vomiting from extensive hepatocelluar damage, a patient's hepatic function panel is analyzed in the laboratory. The result of the ALT is too high for the instrument to read. Since the instrument does not perform automatic dilutions for ALT, the laboratorian performs a dilution using 100 microliters of patient sample to 400 microliters of diluent. The result now reads 369 U/L. How should the laboratorian report this patient's ALT result?
1845 U/L
A technologist pipetted 200 microliters of serum in a test tube and added 5 milliliters of saline to the tube. What is the dilution ratio of serum to the total volume in the tube?
1:26
How many grams of sodium hydroxide are required to prepare a 200 ml solution of a 10% (weight per volume) solution? (Atomic weights: Na = 23; 0 = 16; H = 1)
20g
How many grams of NaOH is required to prepare 500 ml of a 5% (w/v) NaOH solution?
25 grams
How many grams of CaCl2 is needed to prepare 500 mL of a 0.5M solution of CaCl2?
27.5 g
A spinal fluid that is slightly hazy is briefly examined microscopically. The technologist performing the count decides to make a 1:10 dilution using 30 µL of sample. What volume of diluent should be used?
270 µL
A technologist put five (5) tubes in a test tube rack and put 3 mL of diluent in each tube. The tech then put 0.3 mL serum in the first tube and mixed it. Next, the tech then transferred 1 mL of the mixture from the first tube to the second tube. This process was carried on through tube number five (5). What is the dilution factor in tube number five?
2816
What is the molarity of a 3.5 N solution of HCl (gmw=36.46 g/mol, valence=1)?
3.5 mol/L HCl
How many milliliters of 3N solution can be made from 50g of CaCl2?
300 mL
What do you need to make up 450 mL of a 3.8 M solution of NaOH (gmw=39.997 g/mol)?
68.4 g NaOH
What weight of H2SO4 is contained in 200 mL of a 4 molar H2SO4 solution? (Atomic weight: H= 1; S = 32; 0 = 16)
78.4 g
What is the molarity of H2SO4 (GMW = 98) that has a specific gravity of 1.21 and an assay weight of 68% w/v?
8.4 M
What is the normality of 32.1% HCl? (HCl has a positive valence of 1)
8.8N
The process of pipetting 1.0 mL of plasma or serum into a tube containing 1.0 mL of saline, mixing the contents and then repeating the same procedure into several additional tubes also containing 1.0 mL of saline is referred to as:
Two-fold serial dilution
What is the molarity of a 2.5 N solution of H2SO4 (gmw=98 g/mol, valence=2)?
1.2 mol/L H2SO4
What is the normality of a 500 mL solution containing 25g of H3PO4? (H3PO4 has a positive valence of 3)
1.53N
A microliter is equal to:
1/1000 mL
A serum sample is received in the clinical chemistry department of the laboratory. The first time the sample is assayed, the result is 600 mg/dL. To verify this result (following this hospital's policy), the tech makes 2 mL of a 1:2 dilution of the original sample. If only 1 mL of this sample is analyzed, what would the result be? Assume that the original 600 mg/dL value was accurate and that the instrument did not automatically perform a dilution calculation.
300 mg/dL
In order to correctly prepare a 4 M solution of NaOH, how many grams need to be added to 200 mL of solution? (GMW NaOH =40 g)
32 grams
An aqueous 2.00 M HCl solution is prepared with a total volume of 0.475 L. The molecular weight of HCl is 36.46 g/mol. What mass of hydrochloric acid (in grams) is needed for the solution?
34.6 g
A 4.0 mg/dL creatinine standard is needed. To prepare 100 mL of the working standard, how much stock standard of 1 mg/mL creatinine is needed?
4 mL
A 200 mg/dL solution was diluted 1:10. This diluted solution was then additionally diluted 1:5. What is the concentration of the final solution?
4 mg/dL
In order to make a 1:10 dilution with 500 microliters of patient serum, how much saline would be needed?
4.5 mL
You are working in a clinical chemistry laboratory and are analyzing a plasma glucose sample. The sample is flagged by the analyzer for being "outside of linear range." You manually dilute the sample 1:2 and rerun it. Again, you receive an "outside linear range" alert. You decide to perform a different manual dilution. This time you manually dilute the original sample again; this time using a 1:3 dilution. The instrument gives you a glucose value of 150 mg/dL from this diluted sample. What is the actual patient glucose result that you should report to the physician?
450 mg/dL
How do you make up 275 mL of a 4.6 M solution of HCl (gmw=36.46 g/mol)?
46.1 g HCl
The weight of NaCl present in 650 ml of a 0.85% NaCl solution is:
5.53 grams
What is the molarity of an unknown HCl solution that has a specific gravity of 1.10 and an assay percentage of 18.5%? (Atomic weight: HCl = 36.5)
5.6 mol/L
A technologist has 500 µL of serum and needs to make a 1/2 dilution for a glucose determination. How should he/she do it?
500 µL of serum plus 0.5 mL of saline
What mathematically establishes the direct relationship between the concentration of a substance and its absorbance?
Beer's law
Which of the following pipettes is the safest and most accurate tool for dilution of cerebrospinal fluids?
Calibrated automatic pipette
A procedure calls for 6 mL of 1N HCl. A stock solution of 3N HCl is available. How would you prepare the required concentration?
Make a 1:3 dilution of 3N HCl
A technologist decides to make a 1:20 dilution of cerebrospinal fluid (CSF) after briefly evaluating a portion of the sample microscopically. After making the dilution and charging the chambers, the number of cells that are observed in each of the large squares of the hemocytometer is >100. What should the technologist do to obtain the most accurate count?
Make a larger dilution
What is expressed as the number of moles per 1 L of solution?
Molarity