Q: Which formula correctly calculates the number of equivalents for an ion?

$$\mathrm{Eq} = \text{moles of ion} \times \text{ion charge}$$

Q: Which of the following is the correct relationship for calculating normality (N)?

$$N = \dfrac{\text{equivalents}}{\text{L solution}}$$

Question 1

Which of the following best describes an equivalent (Eq) in the context of ions in solution?

Accepted Answer

The number of moles of charge that an ion contributes to a solution.

Question 2

How many equivalents are present in 2 moles of $$\mathrm{Ca$$^{2+}$$}$$ ions?

Accepted Answer

$$4 Eq$$

Question 3

A solution contains $$0.35$$ mole of $$\mathrm{Mg$$^{2+}$$}$$ ions in $$300 mL of $$blood. What is the normality (N) of $$\mathrm{Mg$$^{2+}$$}$$ ions in this sample?

Accepted Answer

$$2.33 N$$

Question 4

Which formula correctly calculates the number of equivalents for an ion?

Accepted Answer

$$\mathrm{Eq} = 	ext{moles of ion} 	imes 	ext{ion charge}$$

Question 5

A patient receives $$750 mL of $$saline containing $$140$$ mEq/L of $$\mathrm{Na^+}. $$How many mEq of $$\mathrm{Na^+}$$ are administered?

Accepted Answer

$$105$$ mEq$

Question 6

If $$1.5$$ mEq of $$\mathrm{Na^+}$$ ions are needed, what mass (in grams) of $$\mathrm{Na^+}$$ ions should be provided? (Atomic mass of Na = $$23 g/$$mol)

Accepted Answer

$$0.035 g$$

Question 7

The concentration of $$\mathrm{Cr$$^{3+}$$}$$ ions in blood is $$105$$ mEq/L. How many mL of blood are needed to obtain $$1.4 g of$$ $$\mathrm{Cr$$^{3+}$$}$$ ions? (Atomic mass of Cr = $$52 g/$$mol)

Accepted Answer

$$240 mL$$

Question 8

Which of the following best defines normality (N) in the context of ionic solutions?

Accepted Answer

The number of equivalents per liter of solution.

Question 9

A $$500 mL $$solution contains $$2.0 	imes 10$$^{-3}$$ M $$\mathrm{K^+}$$ ions. What is the normality (mEq/L) of potassium ions in this solution?

Accepted Answer

$$0.020$$ mEq/L

Question 10

How many equivalents are present in $$3$$ moles of $$\mathrm{Fe$$^{3+}$$}$$ ions?

Accepted Answer

$$9 Eq$$

Question 11

A laboratory technician needs to prepare $$250 mL of a$$ $$50$$ mEq/L $$\mathrm{Na^+}$$ solution. How many moles of $$\mathrm{Na^+}$$ are required?

Accepted Answer

$$0.0125$$ mol

Question 12

Which of the following statements about equivalents is TRUE?

Accepted Answer

1 Eq of $$\mathrm{Ca$$^{2+}$$}$$ contains half as many ions as 1 Eq of $$\mathrm{Na^+}.$$

Question 13

A solution contains $$0.5$$ mole of $$\mathrm{PO_4$^{3-}}$$ ions. How many equivalents of $$\mathrm{PO_4$^{3-}}$$ are present?

Accepted Answer

$$1.5 Eq$$

Question 14

If a solution contains $$0.25$$ mole of $$\mathrm{Al$$^{3+}$$}$$ ions, what is the total charge (in equivalents) contributed by these ions?

Accepted Answer

$$0.75 Eq$$

Question 15

Which of the following is the correct relationship for calculating normality (N)?

Accepted Answer

$$N = \dfrac{	ext{equivalents}}{	ext{L solution}}$$

Question 16

A $$100 mL $$sample of blood contains $$0.010 Eq of$$ $$\mathrm{K^+}$$ ions. What is the normality (N) of $$\mathrm{K^+} in $$this sample?

Accepted Answer

$$0.10 N$$

Question 17

A nurse needs to prepare $$500 mL of a$$ $$20$$ mEq/L $$\mathrm{Cl^-}$$ solution. How many grams of $$\mathrm{Cl^-} ($$atomic mass = $$35.5 g/$$mol) are needed?

Accepted Answer

$$0.355 g$

Equivalents and Normality in GOB Chemistry: Concepts, Calculations, and Applications

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