Chemical Analysis
Limiting/ Excess Reagents
Titration
The Curvature of Titration
Let's Do Some Labs!
100
The 3 dominate methods used to analyze an unknown compound
What are colorimetry, gravimetric analysis and titration
100
The reactant that is completely used up in the reaction
What is the limiting reagent?
100

Label the picture provided

A: burette B: clamp C: titrant D:stand E: Stopcock F: erlenmeyer flask

100
Describe the shape of a curve of a strong acid titrated with a strong base
See white board for answer
100

Which is a precipitate reaction?
SO3 + H2O --> H2SO4
2AgNO3 + Na2S --> Ag2S + 2NaNO3
CH4 + 2O2 --> CO2 + 2H2O

What is number 2?
(2AgNO3 + Na2S --> Ag2S + 2NaNO3)

200
The blue to green color emitted when this burned
What is the color of copper
200

Cu + AgNO3 --> Ag + CuNO3 If 9.21 g of copper forms Silver and you also use 17.9 g of silver (I) nitrate, which is your limiting reagent?

What is Silver (I) nitrate.

200

The following data is collected from the titration of 15.0 mL samples of phosphoric acid with 0.112mol/L potassium hydroxide. Find the concentration of the acid.

                                  Trial 1 Trial 2 Trial 3 Trial 4 

Final buret reading (mL) 19.3   36.9   17.9   35.3

Initial buret reading (mL) 1.22  19.3   0.40   17.9

 Volume added (mL)       ____  ____  ____  ____

What is 4.39 x 10-3 mol/L OR 0.00439 mol/L of acid

200
Describe the shape of a curve of a strong base titrated with a strong acid
See the white board
200
Which indicator would be most useful in identifying the equivalence point of a titration for a solution that has an [H+] of 0.02 at the equilvalence point?
What is cresol red (pH range for color change is 0.0-1.0)
300
The determination of the chemical amount of a substances OR the detection of whether a substance is present
What is the fundamental difference between quantitative and qualitative analysis
300

Al2(SO3)3 + 6 NaOH ----> 3 Na2SO3 + 2 Al(OH)3 Determine the number of grams of excess reagent left over in the reaction.

What is 1.84 grams NaOH

300
Titration 1: strong monoprotic acid with a strong base Titration 2: weak monoprotic acid with a strong base How does the initial pH and equivalence point pH differ between them?
Initial pH of weak acid solution higher, and pH higher at the equivalence point in the titration of a weak acid
300
Describe the shape of a curve of a di-protic acid titrated with a strong base
see white board
300
This apparatus is used in the process commonly as titration.
What is a buret?
400
The use of stoichiometric calculations to determine the concentration of a unknown solution
What is titration analysis
400

A 50.6 g sample of Mg(OH)2 is reacted with 45.0 g of HCl according to the reaction:
Mg(OH)2 + 2 HCl --> MgCl2 + 2 H2O
What is the theoretical mass of MgCl2?

What is 58.6g of MgCl2

400

Predict whether the equivalence point of each of the following titrations is below, above, or at pH 7: 1. NaHCO3 titrated with NaOH 2. NH3 titrated with HCl 3. KOH titrated with HBr

What is above pH 7, below pH 7, at pH 7

400
Describe the shape of a curve of a di-protic base titrated with a strong acid
See board for answer
400
Type of solution in the buret during a titration.
What is the titrant?
500

Why might a chemist need to need to carry out qualitative analysis of a solution? Give an example

To determine whether a compound/substance is present in the sample. Eg. Water testing for toxic or harmful substances.

500

In an experiment 25 grams of chloroform(119.378) and 25 grams of chlorine(70.906) were mixed. Which is the excess reactant? CHCl3 + Cl2 --> CCl4 + HCl

What is chlorine

500

During the titration of HCl with NaOH, a very rapid change in pH occurs

a. when the first addition of known solution is made. b. when roughly equivalent amounts of H3O+ ions and OH- ions become present.
c. at several points.
d. at no point.

What is b?

500
Explain why one might see multiple equivalence points
polyprotic acid/base
500
Thymol blue has two color changes: 1. red to yellow at ~pH 3 2. yellow to blue at ~pH 9 Which color change will generally be more suitable for titration of a weak acid with a strong base?
yellow to blue
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