Q: Which of the following is the correct formula for calculating the percent of analyte in a sample using titration data?

$$\%B = 100 \left[ \frac{V_A(\text{mL}) \ c_A \ R \ MW_B}{\text{mass}_{\text{sample}}} \right]$$

Q: Which of the following is the correct relationship for calculating the number of moles of titrant used in a titration?

$$\text{moles}_A = V_A(\text{L}) \times c_A(\text{M})$$

Question 1

Which piece of equipment is essential for accurately measuring and delivering variable volumes of a titrant during a titration, as shown in the first image?

Accepted Answer

Buret

Question 2

In a titration experiment, the equivalence point is best described as:

Accepted Answer

The point where stoichiometrically equivalent amounts of analyte and titrant are present

Question 3

A student titrates 50.00 mL of HCl with 0.01963 M Ba(OH)$$_2$$ and uses 29.71 mL to reach the endpoint. The balanced equation is $$2	ext{HCl} + 	ext{Ba(OH)}_2 ightarrow 	ext{BaCl}_2 + 2	ext{H}_2	ext{O}. $$What is the molarity of the HCl solution?

Accepted Answer

$$0.02333\ 	ext{M}$$

Question 4

Which property is NOT desirable for a primary standard used in titrimetric analysis?

Accepted Answer

Highly hygroscopic

Question 5

A titration curve with a sigmoidal shape (see image 9) is most commonly associated with which type of titration?

Accepted Answer

Volumetric titration involving a strong acid and strong base

Question 6

A student needs to prepare 5.000 L of 0.1000 M Na$$_2CO$_3 ($$molar mass = 105.99 g/mol) from a primary standard. What mass of Na$$_2CO$_3$$ should be weighed out?

Accepted Answer

$$53.00\ 	ext{g}$$

Question 7

Which of the following best explains the difference between the equivalence point and the endpoint in a titration?

Accepted Answer

The endpoint is when the indicator changes color, which may not exactly coincide with the equivalence point where stoichiometric amounts have reacted.

Question 8

In the titration of 0.2121 g of pure Na$$_2C$_2O$_4 (134.00 g/$$mol) with 43.31 mL of KMnO$$_4$$, the balanced equation is $$2	ext{MnO}_4^- + 5	ext{C}_2	ext{O}_4$$^{2-}$$ + 16	ext{H}^+ ightarrow 2	ext{Mn}^{2+} + 10	ext{CO}_2 + 8	ext{H}_2	ext{O}. $$What is the molarity of the KMnO$$_4$$ solution?

Accepted Answer

$$0.01462\ 	ext{M}$$

Question 9

Which of the following is a secondary standard?

Accepted Answer

A solution whose concentration is determined by titration with a primary standard

Question 10

A 0.8040 g sample of iron ore is titrated with 47.22 mL of 0.02242 M KMnO$$_4. $$The reaction is $$	ext{MnO}_4^- + 5	ext{Fe}^{2+} + 8	ext{H}^+ ightarrow 	ext{Mn}^{2+} + 5	ext{Fe}^{3+} + 4	ext{H}_2	ext{O}. $$What is the percent Fe in the sample? (Molar mass Fe = 55.847 g/mol)

Accepted Answer

$$36.77\%$$

Question 11

Which of the following best describes the role of an indicator in a titration?

Accepted Answer

It signals the endpoint by undergoing a detectable physical change.

Question 12

A titration curve with a linear-segmental shape (see image 10) is most likely observed in which scenario?

Accepted Answer

When the reaction is complete only in the presence of a large excess of reagent or analyte

Question 13

Which of the following is the correct formula for calculating the percent of analyte in a sample using titration data?

Accepted Answer

$$\%B = 100 \left[ \frac{V_A(	ext{mL}) \ c_A \ R \ MW_B}{	ext{mass}_{	ext{sample}}} ight]$$

Question 14

Which of the following is NOT a method for detecting the endpoint in a titration?

Accepted Answer

Observing a change in temperature

Question 15

A student is preparing a standard solution by dissolving a carefully weighed primary standard in a solvent and diluting to a known volume. This method is called:

Accepted Answer

Direct method

Question 16

In the titration of fluoride with calcium perchlorate, $$	ext{Ca}^{2+} + 2	ext{F}^- ightarrow 	ext{CaF}_2(s)$$, a 92.5 mg sample requires 19.80 mL of 0.0500 M titrant. What is the percent F in the sample? (Molar mass F = 19.00 g/mol)

Accepted Answer

$$40.7\%$$

Question 17

Which of the following statements about titration error is correct?

Accepted Answer

Titration error is the difference between the endpoint and equivalence point volumes.

Question 18

Which of the following is the correct relationship for calculating the number of moles of titrant used in a titration?

Accepted Answer

$$	ext{moles}_A = V_A(	ext{L}) 	imes c_A(	ext{M})$$

Volumetric Titrimetry: Principles, Calculations, and Applications

스터디 가이드 - 연습 문제

학습 가이드 - 플래시카드