# 3.3 moles and volumes Flashcards

1
Q

unit conversions

cm^3 -> dm^3

A

divide 1000

2
Q

dm3 -> cm3

A

X 1000

3
Q

Cm3 to ml

A

1cm3=1ml

4
Q

Idm3 to Liters

A

1dm3=1L

5
Q

Calculate

Number of moles

with concentration and volume

A

Conc (mol/dm3) X vol (dm3)

6
Q

What is the

ideal gas equation

A

PV=nRT

7
Q

what are the units for

PV=nRT

A

P- pressure (pa)
V-volume (m3)
n- number of moles (mol)
R- gas constant (J/mol/k)
T- temprature (K)

8
Q

Unit conversion

kPa -> Pa

A

X1000

9
Q

Unit conversion

K->.c

A

-273

10
Q

When do we use the

ideal gas equation

A

differnet temps and pressures for greater accuracy we use the ideal gas equation

11
Q

the ideal gas equation

A
1. the molecules are in random motion
2. elastic collisions
3. negligible size
4. no intermolecular forces
12
Q

In PV=nRT

whats the value of the constant R

A

8.314

13
Q

Define

A standard solution

A

is a solution whose concentration is known.

14
Q

which glassware is used to make a standard solution.

A

15
Q

The tolerances of the volumetric flask

A

16
Q

Where should the meniscus sit?

A

When filling a volumetric flask, the meniscus of the
solution must sit on the graduated line

17
Q

Once made up to the graduation line, the stopper is placed on top and the volumetric flask is
slowly inverted to ensure even mixing. Why?

A

There would be uneven mixing of the substance within the standard solution. Inverting the
flask allows uniform mixing, and an equal concentration throughout.

18
Q

What effect will overfilling the volumetric flask beyond the graduated mark have?

A

Overfilling the volumetric flask, would increase the volume of water in which the substance
has been dissolved. This would decrease the concentration of our solution.

19
Q

Making a standard solution:

A
1. Weigh the exact mass of solid accurately.
2. Dissolve the solid in a beaker using less distilled water than will be needed to fill the volumetric flask to the mark.
3. Transfer the solution to the volumetric flask. The last traces of the solution are rinsed into the flask with distilled water.
4. Fill the flask carefully to the graduation line by adding distilled water a drop at a time until the bottom of the meniscus lines up exactly with the mark.
5. Invert the volumetric flask, slowly, several times to mix the solution thoroughly. (N.B. if this stage is not done, then you will end up with inconsistent results in your titration.)
20
Q

!!! If n = cxV/1000 is used to calculate the concentration, multiplying your answer by the Mr
of the compound will give the concentration in gdm-3

A

If n = cxV/1000 is used to calculate the concentration, multiplying your answer by the Mr
of the compound will give the concentration in gdm-3

21
Q

g/dm3->mol/dm3

A

divide by Mr