SACE STAGE 1 CHEMISTRY UNIT 4 TEST

What is the term Miscible?

Miscibility is the term for liquids that can be mixed to forma homogenous substance

What is the term Immmisible?

Substances that cannot mix to form a miscible substance, but form a heterogeneous substance

What type of molecules are miscible

Substances of the similar polarity are Miscible.

What is a solute

Substance being dissolved

What is a solvent

Substance which the solute is being dissolving in.

Molarity

•the number of moles of solute per litre of solution (molL-1)

How are polar substances able to dissolve together?

Because they can interact with secondary bonding
Polar can use Dipole- Dipole interactions/ hydrogen bonding
nonpolar- dispersion forces

Why can substances of the same polarity be Miscible?

Because their secondary forces are weak, they can make a homogenous solution

What is water?

A universal solvent, so can dissolve a wide range of substances. It can disrupt other secondary reactions

Miscibility is determined by

Polarity and Size

Why does size effect Miscibility

Because as the particles increase in size, it is more difficult for the solvent to seperate and surround them.

Dispersion forces occur more so grow bigger as the substance grows, so are harder to break by water.

What is the biggest hydrocarbon that can be dissolved

propanol

What is a polar head?

A polar head is a portion of a non polar molecule that has a polarity

What are emulsions?

mixture of two liquids that are not mutually soluble

What are Emulsifiers?

Substances that have both hydrophilic (polar) and hydrophobic (non polar ) components that help in mixing two immiscible

What is a hydrophobic component?

a water hating component (non polar)

What is a hydrophilic component

water loving (polar

What are micelles?

•The hydrophobic component of the emulsifier interacts with the grease, The hydrophilic component of the emulsifier interacts with the water
The soap and detergent ions surround the droplets of grease forming micelles.

What is an Ion-dipole force?

an attractive force from a polar molecule's dipole to an ion.

What is an example of an ion-dipole force?

Hydration shells

What is a hydration shell?

When an ionic compound is dissolved in water, each ion is surrounded by a sphere of water molecules
Hydrogen atoms from water are attracted to anion, while oxygen atoms of water are directed towards the cation

What is an aqueous state?

where ions have been pulled apart, dissolved in substance, not solid

Ion Dipole bonds are stronger than

Dipole Dipole bonds

Solubility table

picture

how does a precipitate form

When two dissolved substances combine to form a insoluble substance

What is an example of a precipertate reaction?

AgNO₃ (aq) + NaCl (aq) → AgCl (s) ↓ + NaNO₃ (aq)

What are spectator ions?

ions that do not participate in a reaction

What is dissociation?

the process in which an ionic compound separates into ions as it dissolves, it gains energy to do this (not hydration yet, occurs after)

What is a complete ionic equation

It is an equation that shows all the ions in a solution as they exist, and the precipitate

What is a net ionic equation

an equation for a reaction in solution that shows only those particles that are directly involved in the chemical change

How do you calculate the concentration in mol/l

C=n/V(Litres)

concentration of solution (G/L)

C= m(grams)/V(litres)

ppm=

mg/L

ppb=

u/l

percent weight per volume

%w(grams/ v(mL) 100= g/100ml

Calculate missing value for a dilution

c1v1 (Litres) = c2 xv2 (same mol (balancing the equation)

Dilution

Same mol amount of solute doesnt change, but does per L when more added

Dissociation

absorbs energy, to break bonds (endothermic)
Energy required to pull the substance apart

How to Create a standard solution

Weight out the mass of solute needed for the solution
Transfer the mass of solute to a clean beaker (use solvent to remove excess solute from the surface)

Dissolve the solute in appropriate amount of solvent

Transfer the solution from the beaker to the volumetric flask

funnel used to ensure all of the solution is transferred.

Add solvent until the solution is parrallel with the graduation mark at eye level. (bottom of meniscus)

What is a free hydrated cation/ anion called?

Electrolyte

Mass of substance for standard solution- Moles

n=CxV

What is stoichiometry

The calculation of quantities in chemical reactions

Steps of Stoichiometry

1Balance equation
2Determine moles in substances
3Determine mole ration (reactants to product (eg 2:3))
4multiply element 1’s number of moles by the mole ratio to find element 2’s number of moles , 5determine molar mass, determine mass

What is a endothermic reaction?

A reaction that absorbs energy from the surrounds, cooling surroundings

What is an exothermic reaction

energy is released as new chemical bonds are formed in the products, energy is released to the surrounding :heating effect

Enthalpy

Lattice energy- hydration energy

what is a thermochemical equation

a chemical equation that includes the enthalpy change

Calculate the heat energy absorbed or released in a reaction (Q, measured in Joules):

Q= mass (water in g) x temperature change x 4.18 (water capacity)

Determine the molar enthalpy for a substance/solution (measured in kJ/mol):

Q/1000 x n (substance)

What Ions are present in Hard Water?

magnesium (Mg) and calcium (Ca)

Q=

Mass x Change temperature x 4.18 (for water)

n=

moles

M=

Molar mass

m=

mass

Equation pyramind of m=CV

What are Micelles made up of?

Multiple surfactant molecules that have both a polar head and non polar tail

In Micelles,

there is a polar head, and a non polar tail

How are ionic compounds dissolved in water?

Dissociation and hydration

Dissociation equation

Nacl(s)+ (aq)→ Na⁺(_aq) and Cl^-_(aq)

Hydration

How is an ionic compound dissolved in water?

The ionic compound firstly dissociates in the water, becoming seperated from the lattice structure, becoming single cation and anion ions. After this, the water surrounds the ions and forms ion dipole bonds, forming a hydration shell around the ion.