💊 Amount of Substance

What is a mole?

$6.02\times10^{23}$ particles

What is Avogadro constant?

$$6.02\times10^{23}$$

How to convert between number of particles and moles with Avogadro’s constant?

Num of particles = Num of moles x Avogadro’s constant

How to calculate moles from Mass and$M_{r}$

$$n=\frac{m}{M_{r}}$$

How to calculate concentration from moles?

$$n=\frac{C\times V\left(\operatorname{cm}^3\right)}{1000}$$

What are standard conditions?

100kPa or 1atm

298K or 25∘C

Ideal gas equation?

$pV=nRT$

R= 8.31 ($JK^{-1}mol^{-1}$)

p= pressure (Pa)

V= volume ($m^3$)

T= Temp (K)

What is a balanced equation?

A reaction where the number of reactants and products of all elements are the same on both sides

What is an ionic equation?

An equation where only reacting ions are shown

How to form an ionic equation?

• Balance equation:

$$HNO_3+NaOH\rightarrow NaNO_3+H_2O$$

• Split up ions:

$$H^{+}+Na^{-}+NO_3^{+}+OH^{-}\rightarrow Na^{-}+NO^{-}_3+H_2O$$

• Remove ions that appear on both sides:

$$H^{+}+OH^{-}\rightarrow H_2O$$

• Finished equation:

$$H^{+^{}}+OH^{-}\rightarrow H_2O$$

How to calculate mass of product from reactants?

1. Balance the equation

2. Then find the moles of limiting reactant

3. Then use molar ratio to find moles of product being made

4. Then use this ratio to calculate the mass of the product from the mass of reactant

How to calculate volume of gas from an equation?

1. Balance the equation

2. Then find the moles of limiting reactant

3. Then use molar ratio to find moles of product being made

4. Then put these moles into ideal gas equation

What does state symbol represents solid?

(s)

What does state symbol represents liquid?

(l)

What does state symbol represents gas?

(g)

What does state symbol represents aqueous?

(aq)

What is a universal indicator?

pH indicators that change colours depending on the pH of a solution

What universal indicator do we use in our in school titration?

Phenolphthalein

What is the colour change of phenolphthalein of basic to acid?

Colourless to Pink

Neutralisation reaction?

acid + alkali $\rightarrow$ salt + water

What reaction does titration use?

Neutralisation reaction

What is a standard solution?

A solution you know the exact concentration of

How to make solution of 250$\operatorname{cm}^3$ of a 2.00 $mol$ $dm^{-3}$solution of $NaOH$?

1. Calculate moles of solute:

$n=\frac{C\times V}{1000}$ ,$\frac{250\times2.00}{1000}$ = 0.5 moles

2. Use this to calculate mass of NaOH:

$n=\frac{m}{Mr}$ ,$0.5\times40$ = 20g

3. Place weighing boat on mass balance and weigh 20g of NaOH. Then tip into beaker.

4. The weigh the weighing boat and do: (weighing boat + NaOH) - weighing boat to find precise amount of NaOH used.

5. Then add distilled water to beaker until all dissolved

6. Then pour into conical flask with funnel

7. Rinse funnel, beaker and sides of conical flask with distilled water and pour into flask to get all solute in flask.

8. Fill flask to correct volume- make sure meniscus reaches line (add drop wise at end) - if go over line need to restart

9. Stopper the flask and turn upside down a few times

10. Now calculate concentration of standard solution

How to perform titration?

1. Place known volume of solution with unknown concentration in conical flask

2. Add universal indicator

3. Then place solution of known concentration in burette (use funnel, meniscus and do at eye level)

4. First do rough titre to get rough end point

5. Then do accurate titre and repeat until have 3 concordant (within 0.1$\operatorname{cm}^3$)

6. Then calculate mean volume used from this titration

How calculate concentration from volume of titre?

1. Find moles of solution in burette

2. Write equation and balance

3. Then compare molar ratio and find moles of neutralised solution

4. Then use volume and moles to calculate concentration of unknown solution

CAN DO OPPOSITE FOR VOLUME

What is an Empirical formula?

The smallest whole number ratio of each element present in a compound

What is theoretical yield?

The theoretical maximum amount of products that can be made

What is percentage yield?

$$Percentage.Yield=\frac{Actual.Yield}{Theoretical.Yield}\times100$$

What is atom economy?

The proportion or reactants that become the desired product

What are the economic advantages of high atom economy?

• If there is a high atom economy a higher proportion of the raw materials become useful product, therefore more profitable (less useless by product)

What are the environmental advantages of high atom economy?

• If there is higher atom economy it means less raw materials need to be used to find useful product (so more sustainable as less raw material is used)

• Higher atom economy also means less waste usually chemicals that are harmful to the environment

What are the social advantages of high atom economy?

• If there is a higher atom economy it means more useful product are being produced, therefore more is available so it is cheaper and more accessible to people

Equation for atom economy?

$percentage.atom.economy=\frac{Mr.of.desird.product}{\sum of.Mr.of.reac\tan ts}\times100$