Chemistry Flashcards
(32 cards)
Melting point
The melting point of a substance is the temperature at which it changes from a solid to a liquid (melts).
To identify an unknown substance, the melting point of the substance can be determined and compared to the melting points of known substances.
It is a characteristic property because no two pure substances have the same melting point.
Characteristic property
It is a characteristic property because no two pure substances have the same property.
The boiling point of a substance is the temperature at which it changes from a liquid to a gas (boils/evaporates).
It is a characteristic property because no two pure substances have the same boiling point.
The boiling point of an unknown substance can be determined and compared to the boiling points of known substances.
Density
Density is the ratio (relationship/proportion) between the mass and volume of a substance.
Density is a characteristic property.
The unit used to express density is g/mL or g/cm3 (note: 1 mL = 1 cm3).
A = 1KG
B = 5KG
AREAS ARE THE SAME
B has a higher density than A, because B has a higher mass for the same amount of space occupied.
A = 10KG
B = 10 KG
B AREA IS BIGGER
A has a higher density than B, because for the same amount of mass A occupies less space.
A) M = 20KG, V= 1L
B) M = 40KG, V = 2L
A has a higher density than B, because for the same amount of mass A occupies less space.
Density formula
D = M/V
D = g/ml or g/cm3
Mass formula
M = D x V
Mass (g)
Volume
V = M/D
V = ml or cm3
Concentration
The concentration of a solution is the quantity of dissolved solute in a quantity of solution.
Formula CONCENTRATION
C = M/V
M = C x V
V = C/M
Solubility
Definition: a measure of the maximum amount of solute that can be dissolved in a solvent at a given temperature
It is a characteristic property because no two pure substances share the same solubility for a given temperature.
Saturation/Unsaturation
The solubility of a substance can be determined by slowly dissolving the solute into a solvent until the solute will no longer dissolve.
The saturation level describes how much solute is dissolved in the solvent.
An unsaturated solution has less solute dissolved in it than the maximum amount.
A saturated solution has exactly the maximum amount of solute that can be dissolved, similar to its solubility value. This means if more solute is added, it will not dissolve.
Solid : effect of temperature on solubility
As the temperature increases, the solubility will also increase
To dissolve more solid, heat up the solution
Gas: effect of temperature on solubility
As the temperature increases, the solubility will decrease
To dissolve more gas, cool down the solution
SOLUBILITY CURVES
The solubility of a substance compared to the temperature of the solution can be represented as a graph.
Indicators
Indicators are substances that change colour, because of a chemical change, when in the presence or absence of a chemical species such as an acid or a base.
Blue and red litmus paper
Acid; base or neutral substance
Red = acid
Blue = base
Red stays red + blue stays blue = neutral
pH paper
Specific pH of a substance
Paper turns a different colour and you compare it to a colour chart to find out the pH
Cobalt chloride paper
Water
The paper changes colour in the presence of water
The paper stays blue when there is no water present
Iodine
Starch
Starch turns blue in the presence of iodine
Limewater test
Carbon dioxide
If the clear, colourless limewater turns milky white, CO2 is present
Solutions
A solution consists of a solute dissolved in a solvent.
In an aqueous solution, the solvent is water.
The solute is the substance that is dissolved in the water.