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Acids & Bases 2

Last updated about 1 year ago

8 questions

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1

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2

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4

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Question 1

1.

Which piece of apparatus is used to add small measured volumes of one reactant to the other reactant during a titration?

Pipette

Burette

Measuring cylinder

Question 2

2.

Which piece of apparatus is used to accurately measure the volume of a reactant before transferring it to a conical flask?

Pipette

Burette

Measuring cylinder

Question 3

3.

If the initial reading in a titration is 0,50 cm3 and the final reading is 26,95 cm3, what is the titre (volume)?

26.95 cm3

27.45 cm3

26.45 cm3

Question 4

4.

12,0 cm3 of 1,00 mol.dm-3 base NaOH has been added to 5,0 cm3 of 2,00 mol.dm-3 HCl.
They react as: HCl + NaOH → NaCl + H2O. Which of the following statements is true?

The system is at the equivalence point

To reach the equivalence point, you need to add more NaCl

To reach the equivalence point, you need to add more NaOH

To reach the equivalence point, you need to add more HCl.

Question 5

5.

At which point in a titration does this graph represent?

The beginning, before the equivalence point

Before starting the titration, the set-up

The middle, right at the equivalence point

The end, once the equivalence point has been determined

Question 6

6.

You are titrating a base into a standard solution of acid and reach the equivalence point but the tap on the burette sticks, causing you to add a few extra drops of base into the acid. How will your calculated concentration of the base be affected? The calculated value will be ....

Higher than it really is

Lower than it really is

About the same as the actual value

Question 7

7.

Match the following titration set-ups with the corresponding titration curve:

Draggable item		Corresponding Item

Question 8

8.

Consider the following information regarding pH indicators:

At a low pH, a weak acid indicator is almost entirely in the HIn form, the colour of which predominates. As the pH increases - the intensity of the colour of HIn decreases and the equilibrium is pushed to the right. Therefore the intensity of the colour of In- increases. An indicator is most effective if the colour change is distinct and over a low pH range. For most indicators the range is within ±1 of its pH at its Ka value and at the point of changing colour [HIn] = [In-].

Consider an indicator that ionized as shown below for which its Ka = 1.0 x 10-4

Which of the responses are true statements? Select all that apply:

The predominant color in its acid range is yellow.

In the middle of its color change a solution containing the indicator will probably be orange

At pH = 7.00, a solution containing this indicator (and no other coloured species) will be red. (Hint: Write the equilibrium constant expression for the indicator.)

At pH = 7.00, most of the indicator is in the un-ionized form

The pH at which the indicator changes colour is pH = 4