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Chemistry Year 12 > Moles ✅ > Flashcards

Moles ✅ Flashcards

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1
Q

What is an isotope

A

Atoms that have the same number of protons but different number of neutrons, same atomic number, different mass number

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2
Q

Link equation with mass, moles, molar mass

A

Moles=mass/Mr

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3
Q

What is the empirical formula

A

Simplest whole number ratio of atoms of the elements in it

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4
Q

11.25g of hydrated cooper sulphate CuSO4.XH2O heated until it loses all of its water, new mass is 7.19g what is value of X

A

11.25-7.19= 4.06g of H2O
Moles of H2O=4.06/18=0.2255

Moles of CuSO4=7.19/159.6=0.0451

Ratio of CuSO4:H2O
1:5
X=5

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5
Q

What is the water of crystallization practical method

A

Weigh a crucible with its lit

Add between 1.3-1,5g of hydrated sulphate crystals, reweigh crucible

Place crucible containing hydrated sulphate on to a clay pipe triangle and gently heat for 2 minutes, take lid off periodically and carefully move crystals around with spatula whilst holding crucible with tongs

Allow contents to cool and re weigh crucible, it’s lid and contents

Continue to reheat and reweigh crucible lid and contents until mass is observed, allow to cool before reheating each time

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6
Q

What is the equation of moles of a gas

A

Volume (dm^3)=24Xmoles

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7
Q

What is the equation for density of a gas

A

Density (g cm^-3 or g dm^-3)= mass (g)/volume (cm^3 or dm^3)

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8
Q

Find volume of Hydrogen gas at room temp and pressure formed when 0.54g of calcium reacts with HCL
Ca+2HCl=CaCl2+H2

A

0.54/40.1=0.013467X24=0.323dm^3

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9
Q

A gas has a density of 3.4916g dm^-3, what is the Ar of a gas and what’s its identity

A

3.4916X24=83.718=Kr

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10
Q

What is the limiting reactant

A

In chemical reactions it is the substance that is used up first and stops the reaction

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11
Q

What mass of aluminum chloride is formed when 13.5g of aluminum reacts with 42.6g of chlorine
2Al+3Cl2=2AlCl3

A

Moles of Al=13.5/27=0.5
Moles of Cl2=42.6/71=0.06478

Al=2=0.5
Cl=3=0.6 so limiting reactant

So 0.6478moles of AlCl3/3 X2=0.4
0.4X133.5=53.4g

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12
Q

What is the equation for percentage yield

A

Percentage Yield = (Actual Yield/Theoretical Yield) x 100

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13
Q

What is the equation for atom economy

A

Atom economy=mass of wanted product from equation/total mass of products from equation

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14
Q

What is relative formula mass

A

Compares the mass of a formula unit with the mass of an atom of carbon-12, calculated by adding together the relative atomic masses of the elements in the empirical formula

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15
Q

What is the definition of water crystallisation

A

when some compounds can form crystals which have water within part of their structure

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16
Q

What is the equation for moles, concentration, volume of a solution

A

Moles=concentration (mol/dm^-3) X volume (dm^3)

17
Q

What number is avogadro constant

A

6.02X10^23

18
Q

What is relative formula mass

A

Compares the mass of of a formula unit with the mass of an atom of a carbon 12

19
Q

Definition of concentration

A

the amount of a substance that is dissolved per unit volume of solution

20
Q

What is theoretical yield

A

Maximum possible amount of product

21
Q

What is atom economy

A

A measure of how well atoms have been utilized s

22
Q

Why are reactions with high atom economy good

A

Produce a large proportion of desired products and few unwanted waste products

Are important for sustainability see they make the best use of natural resources

23
Q

Definition of an acid

A

a substance which in an aqueous solution will release H+ ions.

Acids are also known as proton donors as they release a proton in the form of a H+ ion.

24
Q

What is a weak acid

A

Eg Ethanoic acid (CH3COOH), only releases a small proportion of its available hydrogen atoms into solution as H+ions

A weak acid partially dissociates in aq solution

25
Q

What is a strong acid

A

Eg HCL, releases all its hydrogen atoms into solution as H+ions and completely dissociates in aq solution

26
Q

What is a base

A

A base neutralizes an acid to form a salt

27
Q

What is an alkali

A

A base that dissolves in water releasing OH- into the solution

28
Q

How to prepare a standard solution for titration

A

Solid is weighed accurately

Solid is dissolved in a beaker using less distilled water then will be needed to fill volumetric flask to the mark

Solution transferred to volumetric flask, rinsed with distilled water into flask

Flask filled to graduation line by adding distilled water until bottom of meniscus level

Volumetric flask inverted several times s

29
Q

Describe the titration procedure

A

Add a measured volume of one solution to a convivial flask using a Pipette

Add other solution to a burette record reading let little bit out

Add few drops of indicator to conical flask and swirl

Run the solution of burette into conical flask and swirl until indicator changes colour record final burette reading= rough titration

Repeat 3 times, only calculate Concordant results

30
Q

Work out unknown concentration of h2SO4
25cm^3 of 0.1moldm^3 KOH, mean titre= 25.7 of H2SO4
2KOH+H2SO4=K2SO4+2H2O

A

Moles of KOH= 0.1X0.025=0.0025

Ratio of KOH:H2SO4
2. : 1
0.0025:0.00125

0.00125/0.00257=0.0486moldm^-3

31
Q

What is the ideal gas equation

A

PV=NrT

32
Q

What are the 2 assumptions for the water of crystallization practical

A

All water has been lost

No further decomposition after heating

33
Q

What is 1 dm3 equal to in Ml, L, Cm

A

1000ml
1L
1000cm3

34
Q

What are the units for the ideal gas equation

A

Volume=m3
Pressure= Pa
Mol
Ideal gas constant= 8.31J mol-1 K-1
Temperature= K (273= 0 degrease)

Chemistry Year 12 (5 decks)

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