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Chem lab finals (tricky only, no math)

1.

What is the law of conservation of mass?

Matter cannot be created nor destroyed, only transformed.

2.

Why are the group 1 metals called "alkali metals"?

When reacting with water they form alkaline hydroxides

3.

What is the electron configuration of H+? Of H-?

H+: 1s0

H-: 1s2

4.

Define A, a, b and c in the equation A=abc.

A-absorbance

a- absorptivity constant

b- cell width

c- concentration (of absorbing species)

5.

Of sodium, potassium, calcium, magnesium and zinc, which would you expect to react the least/littlest?

Zinc

6.

What is the purpose of phenolphthalein?

To detect the presence of a base/low pH.

7.

Define titration

To find the exact volume of one reagent required to exactly react with another reagent.

8.

Define analyte

The analyzed reagent in a titration.

9.

Define titrant

The reagent used to analyze another reagent in a titration.

10.

Define the terms equivalence point and end point.

Equivalence point: when the number of mols of acid and base are equal

End point: When the indicator changes colour

11.

How many Hs does a monoprotic acid have? A diprotic acid? A triprotic acid?

1,2,3

12.

What is the purpose of phenolphthalein?

To detect the presence of a base/high pH.

13.

What is the generic equation for a monoprotic acid reacting with NaOH?

HA(aq)+ NaOH(aq) -> NaA(aq) + H2O(l)

14.

What is the generic equation for a diprotic acid reacting with NaOH?

H2A(aq)+ 2NaOH(aq) -> Na2A(aq) + 2H2O(l)

15.

What is the generic equation for a triprotic acid reacting with NaOH?

H3A(aq)+ 2NaOH(aq) -> Na3A(aq) + 3H2O(l)

16.

Define A, a, b and c in the equation A=abc.

A-absorbance

a- absorptivity constant

b- cell width

c- concentration (of absorbing species)

17.

What is the generic equation for a triprotic acid reacting with NaOH?

H3A(aq)+ 3NaOH(aq) -> Na3A(aq) + 3H2O(l)

18.

Define A, a, b and c in the equation A=abc.

A-absorbance

a- absorptivity constant

b- cell width

c- concentration (of absorbing species)

19.

What does the symbol %T represent in the equation A=2-log %T

Percent transmittance

20.

Why must HCl be handled with care? (2)

It can cause severe burns and respiratory irritation

21.

How would a blank cell for spectrometry be prepared?

With the appropriate ratios of every component except the one which causes the colour you will measure.

22.

1 ppm = 1 ___/____ What are the missing units?

1 ppm = 1 mg/L

23.

What is the formula for pH?

pH = -log[H+]

24.

What is the formula for Ka?

Ka = [H+][A-]/[HA]

25.

What is the formula for pKa?

pKa = -log Ka

26.

log n = a can be rewritten as n = what?

n = 10a

Ex. log (339) = 2.530 becomes 339 = 102.530

27.

What does M mean? What is it called (in words)

g/mol, molar mass