Topis - Concentration of solutions
1.
Define
solution" ?
2. Define
the
term & concentration" ?
[1]
3.
How does change in temperature changes the
molarity and molality value ?
[1]
4. calculate the volume
added to 20 ml of
solution to 0.2 m?
of water which could be
0.65 m Hcl to dilute the
[2]
5. is solution is prepared by dissolving 11 g
glucose in 200 cm3 water at 30°C. What is
the mass Percentage of glucose in solution ? The
density of water 30°C is 0.996 g/cm3 7 [2].
Answers
Answer:
- A solution is a homogeneous mixture of two or more substances.
- concentration refers to the amount of a substance in a defined space. Another definition is that concentration is the ratio of solute in a solution to either solvent or total solution. ... Instead of volume, concentration may be per unit mass.
- Molarity is efffected by the temperature because it is based on the volume of the solution, and a volume of the substance will be affected by changes in temp.in general,volume will increase when temp increases,and vice versa. ... mass is the same at any temp hence molality wont change in the change of the temp.
- Up 1st one.
- Up 2nd one.
In chemistry, concentration of a solution is often measured in molarity (M), which is the number of moles of solute per liter of solution. This molar concentration (ci) is calculated by dividing the moles of solute (ni ) by the total volume (V) of the:
c
i
=
n
i
V
The SI unit for molar concentration is mol/m3. However, mol/L is a more common unit for molarity. A solution that contains 1 mole of solute per 1 liter of solution (1 mol/L) is called “one Molar” or 1 M. The unit mol/L can be converted to mol/m3 using the following equation:
1 mol/L = 1 mol/dm3 = 1 mol dm−3 = 1 M = 1000 mol/m3
Calculating Molarity
To calculate the molarity of a solution, the number of moles of solute must be divided by the total liters of solution produced. If the amount of solute is given in grams, we must first calculate the number of moles of solute using the solute’s molar mass, then calculate the molarity using the number of moles and total volume.
Calculating Molarity Given Moles and Volume
If there are 10.0 grams of NaCl (the solute) dissolved in water (the solvent) to produce 2.0 L of solution, what is the molarity of this solution?
First, we must convert the mass of NaCl in grams into moles. We do this by dividing by the molecular weight of NaCl (58.4 g/mole).
10.0
grams NaCl
×
1 mole
58.4
g/mole
=
0.17
moles NaCl
Then, we divide the number of moles by the total solution volume to get concentration.
c
i
=
n
i
V
c
i
=
0.17
moles NaCl
2
liters solution
c
i
=
0.1
M
The NaCl solution is a 0.1 M solution.
Calculating Moles Given Molarity
To calculate the number of moles in a solution given the molarity, we multiply the molarity by total volume of the solution in liters.
How many moles of potassium chloride (KCl) are in 4.0 L of a 0.65 M solution?
c
i
=
n
i
V
0.65
M
=
n
i
4.0
L
n
i
=
(
0.65
M
)
(
4.0
L
)
=
2.6
moles KCl
There are 2.6 moles of KCl in a 0.65 M solution that occupies 4.0 L.
a