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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