Moles nad Avogadros constant

What are the steps for preparing a standard solution?

• Place a weighing boat on a balance and zero the balance

• Add the required mass of solute (solid) to the weighing boat and record the mass to two decimal places

• Transfer all the solid into a 250cm cubed beaker. Use distilled water to rinse the weighing boat into the beaker to ensure all solid has been transferred.

• Add a small amount of distilled water to the beaker, and use a stirring rod to ensure that all of the solute dissolved.

• Transfer the solution to a 250cm cubed volumetric flask using a funnel.

• Rinse the beaker and the stirring rod with more distilled water and transfer these washings to the volumetric flask

• Add distilled water to the volumetric flask until you almost reach the graduation mark

• Carefully add water drop wise using a dropping pipette until the bottom of the meniscus sits on the graduation mark

• Put in a stopper and invert several times

What is a solute?

The solid that will dissolve in the solvent to form a solution

What is a solvent?

The liquid medium that the solute will dissolve in to form a solution

What is a solution?

The homologous mixture created when a solute dissolves in a solvent

What is an acid?

Proton donor

What is a strong acid?

A proton donor that fully dissociates in water

What is a weak acid?

A proton donor that dissociates in water

What is a monoprotic acid?

An acid that donates one H+ per molecule of acid

What is a base?

A proton acceptor

What is an alkali?

Alkalis are proton acceptors and soluble bases containing OH- ions

What is formed when an acid and alkali react?

A salt and water

When acid and alkali react, how is the formula of the salt formed?

The element in the alkali replaces the H+ in the acid.

What is the formula for moles?

Moles = mass/Mr

What is L?

Avogadros constant: 6.022 × 10 ²³

What is a strong monoprotic acid?

A proton donor, which dissociates completely and donates one H+ ion per molecule of acid.

How do you calculate the pH of a strong monoprotic acid?

-log10[CONCENTRATION GIVEN/CALCULATED] =pH

What is an oxidation state?

The + or - number that tells us how many electrons an element has donated or accepted in a chemical reaction.

What is oxidation?

Loss of electrons

What is reduction?

Gain of electrons

What is the oxidation state of uncombined elements (Mg, Na, Al etc)

0

What the oxidation state of diatomic molecules?

0

What is the oxidation state of silver ions?

+1

Whats the oxidation state of Zinc ions?

+2

Whats the oxidation state of Hydrogen

+1 unless bonded to a metal ion

What is the oxidation state of aluminium ions?

+3

What is the oxidation state of all group 1 ions?

+1

What is the oxidation state of all group 2 ions?

2+

Transition metals have positive ot negative oxidation states?

Positive

What is the oxidation state of oxygen?

-2 unless bonded to fluorine or a peroxide

What is the oxidation state of a halogen?

-1 unless Cl/Br/I is bonded to oxygen

What does time of flight mass spectrometry tell us?

Information about relative isotopic mass and the relative abundance of isotopes

What is electron impact ionisation? (Simple)

High energy electroms fired from electron gun

What is electro spray ionisation? (Simple)

Sample dissolved in volatile solvent, forced through fine needle tip connected to positive terminal of a high voltage supply, creating a fine mist which are ionised by gaining H+ ions from the solvent as they leave the tip.

What type of ionisation is used for small molecules?

Electron impact

What kind of ionisation is used for large molecules?

Electro spray

Describe the steps of ionisation for ToF mass spectrometry

• ionisation

• Acceleration - positive ions are attracted towards a negatively charged plate and accelerated towards it so they all have the same kinetic energy

• Positive ions travel through a hole in a negatively charged plate into a flight tube.

• Ions hit a negatively charged plate which generates a current as they gain an electron

What is the ideal gas equation?

PV = nRT

In the ideal gas equation, what is the unit for volume?

M³

In the ideal gas equation, what is the unit for temperature, how do you convert?

Kelvin (K), add 273 onto Celsius

When can you use ½ if you’re balancing equations?

Only in front of diatomic molecules

What is stoichiometery?

The ratio of moles in a balanced equation

In a titration, where is the acid and base usually?

Base in burrette, acid in conical flask.

in a titration, is the indicator oit in the acid or base?

Acid

What kind of acid and base are show in this graph?

Strong acid strong base

What kind of acid and base are shown in this graph?

Strong acid weak base

What kind of acid and base are shown in this graph?

Weak acid weak base

What kind of acid and base are shown in this graph?

Weak acid strong base

Whats the oh range of Methyl Orange?

2.9-4.0

When should the indicator change colour?

When the end point is reached

What is the end point on a graph?

The vertical line showing pH increase

What is the pH range for bromothymolblue?

6.0-7.6

What is the pH range for phenolphthalein?

8.2-10.0

What is the pH range for Alizorin Yellow?

10.1-12.0