end of year revision Y10-Chemistry Flashcards

Question

Why atoms react with other atoms ?

Answer 1

atoms react with other atoms in order to achieve a full outer shell of electrons (which would make them more stable)

Answer 2

Electronic configuration

Answer 3

The elements in group 0 of the periodic table are called the noble gases They are all non-metal, monatomic (exist as single atoms), colourless, non-flammable gases at room temperature The group 0 elements all have full outer shells of electrons, they do no need to participate in reactions to complete their outer shells by losing, gaining, or sharing electrons. therefore they are unreactive and extremely stable

Answer 4

1.\_\_\_P4 + \_**5**\_O2 à **\_2\_**P2O5

Answer 5

Formula unit mass for (NH4)2SO4 =2×atomic mass of N+8×atomic mass of H+1×atomic mass of S +4×atomic mass of O =2×14+8×1+1×32+4×16 =28+8+32+64 **=132** **132 g/mol**

Answer 6

The molar mass of sucrose is 342.3 g mol-1 The number of moles is found by mass ÷ molar mass This comes to 2.64 g ÷ 342.3 g mol-1 = **7.71 x 10-3 mol**

Answer 7

Answer: From the periodic table the relative atomic mass of Zn is 65.38 So, the molar mass is 65.38 g mol-1 The mass is calculated by moles x molar mass This comes to 0.250 mol x 65.38 g mol-1 = **16.3 g**

Answer 8

Actual yield of copper(II) sulfate = 1.6 g Percentage yield of copper(II) sulfate = (1.6 / 2.0) x 100 **Percentage yield = 80%**

Answer 9

Step 1 - Calculate the relative formula mass of the empirical formula (C x 4) + (H x 10) + (S x 1) = (12 x 4) + (1 x 10) + (32 x 1) = 90 Step 2 - Divide the relative formula mass of X by the mass of the empirical formula 180 / 90 = 2 Step 3 - Multiply each number of elements by 2 (C4 x 2) + (H10 x 2) + (S1 x 2) = (C8) + (H20) + (S2) Molecular Formula of X = C8H20S2

Answer 10

gives the simplest whole number ratio of the atoms present in a compund. It can be worked out from experimental data

Answer 11

kinetic energy

Answer 12

Concentration

Answer 13

a technique used to follow the course of a neutralisation reaction between an acid and an alkali. it can be used to find out how much of an acid/alkali reacts with a certain volume of an alkali/acid

Answer 14

Method: Use the pipette and pipette filler and place exactly 25 cm3 sodium hydroxide solution into the conical flask Place the conical flask on a white tile so the tip of the burette is inside the flask Add a few drops of a suitable indicator to the solution in the conical flask Perform a rough titration by taking the burette reading and running in the solution in 1 – 3 cm3 portions, while swirling the flask vigorously Quickly close the tap when the end-point is reached (sharp colour change) and record the volume, placing your eye level with the meniscus Now repeat the titration with a fresh batch of sodium hydroxide As the rough end-point volume is approached, add the solution from the burette one drop at a time until the indicator just changes colour Record the volume to the nearest 0.05 cm3 Repeat until you achieve two concordant results (two results that are within 0.1 cm3 of each other) to increase accuracy

Answer 15

31.9 g of CuSO4 RFM 63.5 + 32 + (4x16) = 159.5 g/mol Moles of anhydrous = 31.9/159.5 = 0.2 moles So, moles of hydrated crystal must have been = 0.2 moles Using formula triangle? Mr of hydrated crystal = mass/moles = 49.9/0.2 = 249.5g/mol What is the total mass of the waters of crystallisation? 249.5 - 159.5 = 90 g/mole So, moles of water =90/18 = 5 **So formula of the hydrated crystal is CuSO4.5H2O**

Answer 16

* 2H2 + O2 → 2H2O * Moles of H2 = 14/2 = 7 moles. • •Moles of O2 = 7/2 (from 2: 1 ratio) 3.5 moles. • * Volume of O2? * 3.5 x 24dm3 = 84dm3

Answer 17

* CH4 + 2O2 → CO2 + 2H2O * Moles of CH4 (Mr =16) * 36/16 = 2.25 moles • •Moles of CO2 = 2.25 moles (1:1 ratio in the equation) • * Volume of CO2? * 2.25 x 24 = 54dm3 * Volume of O2needed? * 1: 2 ratio fromCH4 = 4.5 moles 2:1 ratio from CO2 volume! 108dm3

Answer 18

Write out the formulae of each ion, including their charges Al3+ SO42- Balance the charges by multiplying them out: Al3+ x 2 = +6 and SO42- x 3 = -6; so +6 – 6 = 0 So the formula is Al2(SO4)3

Answer 19

strong electrostatic force of attraction between oppositly charged ions formed by the transfer of electrones from one atom to another

Answer 20

charged particle formed when an atom loses or gains electrones

Answer 21

the arrangement of ions in an ionic compound in its solid state

Answer 22

force of attraction betwwen covalent molecules much weaker than covalent bonds within the molecules

Answer 23

trong electrostatic force of attraction between the nuclei of the atoms making up the bond and the shared pair of electrons

Answer 24

because the shared pair of electrons is attracted to the nucleus of both atoms forming a strong bond

Answer 25

because of the weak intermolecular forces between mulecules that doesn’t take much energy to break

Answer 26

They have low melting and boiling points as they have weak intermolecular forces acting between the molecules that doesn’t take much energy to break

Answer 27

What is a molecule?•A group of atoms held together by covalent bonds

Answer 28

* A shared pair of electrons * (Attracted to the nucleus of both atoms).

Answer 29

covalent bonds have no ions, and no mobile electrons,

Answer 30

because giant structue has **no** small molecules or ions that can be seperated by solvent molecules

Answer 31

diamond has a giant covalent structure held together by strong covalent bonds graphite has layers that are held together by delocalised electrones , layers can slide over each other making it easy to be flaked off

Answer 32

has a giant structure held together by stron covalent bond that require a lot of energy to break it

Answer 33

**SiO2** 1. Giant covalent structure 2. Held together by Strong covalent bonds 3. Lots of energy required to break them. **CO2** 1. Simple molecular covalent 2. Weak intermolecular forces 3. Not much energy required to break them.

Answer 34

it has layers and between layers has delocalized electrones that can move and conduct electricity

Answer 35

Ionic compounds are held together by strong electrostatic forces of attraction between oppositely charged ions. These compounds have high melting points and high boiling points because of the large amounts of energy needed to break the many strong bonds.

Answer 36

forces between molecules

Answer 37

is the electrostatic attraction between the lattice of positive metal ions and the sea of delocalised electrons”

Answer 38

When layers slide past each other in an ionic substance. The like-charged ions are forced next to each other. The ions repel. The ionic bonding is disrupted.

Answer 39

Covalent compounds cannot conduct electricity hence they do not undergo electrolysis