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Flashcards in Stoichiometry Deck (12)
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1
Q

STP

A

T = 273 K

22.4 L/mol

2
Q

What happens when not all organic vapor fully displaces air from flask when heat removed?

A

The flask would not be 100% organic vapor -> decreased yield

3
Q

What happens to compounds in combustion analysis?

A

Compounds oxidized and oxide gas collected

ex. CO2, SO2

4
Q

Why can’t the mass percent of oxygen in a compound be determined directly using combustion/elemental analysis

A
  • when the carbohydrate is oxidized, the oxygen can be found in both water and carbon dioxide
  • procedure involves adding excess oxygen so the oxygen from carbohydrate and oxygen reactant cannot be distinguished
  • oxygen is already fully reduced in carbohydrate and does not react with oxygen gas to be oxidized
5
Q

Two solutes with the same mass percent, which one has highest molarity?

A

The solute with the lowest molecular weight would have the greater number of moles.

6
Q

Why is water rinsed through a pipet after it transfers solution?

A

To ensure complete transfer of the solution. In addition, the rinsing is not quantitative and doesn’t measure volume, the flask with the solution measures volume.

7
Q

What is a ten-fold dilution?

A

A ten-fold dilution is defined as a dilution that results in a final concentration of a solution
that is ten percent of its original concentration. Final volume should be ten times initial volume.

8
Q

How to make the greatest dilution?

A

The greatest dilution results from the greatest relative addition of solvent.

9
Q

Adding solvent to a solution dilutes the solution and decreases?

A

Decreases molarity, molality, percent solution

NOT density, it depends on relative density of the solvent and solution, so density can increase or decrease

10
Q

Increasing density of solution does what to molarity and molality?

A

Increases both molarity and molality because greater concentration of solute

11
Q

Wavelength of colors?

A
700nm = red
400nm = purple
12
Q

Negative value for change in entropy means….

A

Gain in order, losing randomness so the number of molecules probably decrease too