The standard units used for this equation are
$P$ in Pa,
$V$ in m
${}^{3}$ and
$T$ in K. Remember also that 1000cm
${}^{3}$ = 1dm
${}^{3}$ and 1000dm
${}^{3}$ = 1m
${}^{3}$ .
A sample of gas occupies a volume of 20 dm
${}^{3}$ , has a temperature of 280 K and has a pressure of 105 Pa. Calculate the number of moles of gas that are present in the sample.
The only value that is not in SI units is volume. V = 0.02 m
${}^{3}$ .
An enclosed gas(i.e. one in a sealed container) has a volume of 300 cm
${}^{3}$ and a temperature of 300 K. The pressure of the gas is 50 kPa. Calculate the number of moles of gas that are present in the container.
What pressure will 3 mol of gaseous nitrogen exert if it is pumped into a container that has a volume of 25 dm
${}^{3}$ at a temperature of 29
${}^{0}$ C?
The volume of air inside a tyre is 19 litres and the temperature is 290 K. You check the pressure of your tyres and find that the pressure is 190 kPa. How many moles of air are present in the tyre?
Compressed carbon dioxide is contained within a gas cylinder at a pressure of 700 kPa. The temperature of the gas in the cylinder is 310 K and the number of moles of gas is 13 moles of carbon dioxide. What is the volume of the gas inside the cylinder?
Molar concentrations of liquids
A typical solution is made by dissolving some solid substance in a liquid. The amount of substance that is dissolved in a given volume of liquid is known as the
concentration of the liquid. Mathematically, concentration (C) is defined as moles of solute (n) per unit volume (V) of solution.
$$C=\frac{n}{V}$$
For this equation, the units for volume are dm
${}^{3}$ . Therefore, the unit of concentration is mol.
${\mathrm{dm}}^{-3}$ .
When concentration is expressed in mol.
${\mathrm{dm}}^{-3}$ it is known as the
molarity (M) of the solution. Molarity is the most common expression for concentration.
Do not confuse molarity (M) with molar mass (M). Look carefully at the question in which the M appears to determine whether it is concentration or molar mass.
Concentration
Concentration is a measure of the amount of solute that is dissolved in a given volume of liquid. It is measured in mol.dm
${}^{-3}$ . Another term that is used for concentration is
molarity (M)
If 3.5 g of sodium hydroxide (NaOH) is dissolved in 2.5
${\mathrm{dm}}^{3}$ of water, what is the concentration of the solution in mol.
${\mathrm{dm}}^{-3}$ ?
$$n=\frac{m}{M}=\frac{3.5}{40}=0.0875mol$$
$$C=\frac{n}{V}=\frac{0.0875}{2.5}=0.035$$
The concentration of the solution is 0.035 mol.dm
${}^{-3}$ or 0.035 M
You have a 1 dm
${}^{3}$ container in which to prepare a solution of potassium permanganate (KMnO
${}_{4}$ ). What mass of KMnO
${}_{4}$ is needed to make a solution with a concentration of 0.2 M?
$$C=\frac{n}{V}$$
therefore
$$n=C\times V=0.2\times 1=0.2mol$$
$$m=n\times M=0.2\times 158.04=31.61g$$
The mass of KMnO
${}_{4}$ that is needed is 31.61 g.
Think about it like this:
Okay so you're in a car right and it's going straight right?
The car then suddenly takes a sharp right turn, have you noticed that your body resists going to the right, so it kinda goes in the opposite direction /the direction the car was originally going in.
Tlotliso
This is called inertia so your body is resisting the change in its motion.
Tlotliso
So basically newton's first law states that and object will CONTINUE in its state of rest/uniform velocity in a straight line unless it is acted upon by a resultant force.
Aim : investigate the relationship between force and acceleration
Hlumelo
The relationship between force and direction is directly proportional, which means that when force increases acceleration increases and if it decreases so does acceleration
Akhona
Law of Acceleration - The acceleration of an object is directly proportional to the force acting on it and inversely proportional to the mass of the object.