topic 1: principles of chemistry Flashcards

Question

elements

Answer 1

consists of one type of atom only

Answer 2

no chemical bonds between the different components in a mixture unlike a compound

Answer 3

completely made up of a single element or compound has a specific melting/boiling point unpure stuff boils gradually over a range of temperature

Answer 4

separates an insoluble solid from a liquid put some filter paper into a funnel and your mixture into it. the liquid part of the mixture runs though the paper leaving behind a solid resid

Answer 5

separates a soluble solid from a solution pour the mixture into an evaporating dish and gently heat the solution once some of the water has evaporated/you see crystals forming, remove the dish from the heat and leave the solution to cool the salt should form crystals as it becomes insoluble in the cold, more concentrated solution filter the crystals out and leave in a warm place to dry (or a drying oven)

Answer 6

rock salts simply consist of salt and sand grind up the rock salt with a pestle and mortar dissolve in a beaker and stir filter through filter paper in a funnel to get rid of insoluble sand crystallisation!!!

Answer 7

distance travelled by solute/distance travelled by solvent

Answer 8

separates out mixtures draw a line near the bottom of a sheet of filter paper using a pencil add spots of different inks to the line at regular intervals + loosely roll up and put it in a beaker of solvent e.g water or ethanol ensuring the level is below the baseline place a lid to prevent the solvent from evaporating the solvent will seep up the paper to carry the inks with it when the solvent has nearly reached the top of the paper, take the paper out of the paper and leave it to dry

Answer 9

provides surface for the solvent+inks to travel up

Answer 10

the solvent that travels

Answer 11

separates solutions heat the solution. the one with the lower boiling point evaporates the vapour is then cooled, condenses, and is collected the rest of the solution is left behind the flask

Answer 12

can only use it to separate things with very different boiling points

Answer 13

used to separate a mixture of liquids put the mixture in a flask and stick a fractioning column on top. then heat it the different liquids all have different boiling points, so they are able to evaporate at different temperatures the liquid with the lowest point evaporates first, reaching the top of the column. it will then condensed to be collected all the other liquids will also evaporate, however they will only manage to make it halfway before condensing since the top is cool repeat with different temperatures

Answer 14

periods: amount of shells groups: amount of electrons in the outer shell

Answer 15

more located on the right poor conductors of electricity non metal oxides are acidic. they neutralise bases. they dissolve in water to form solutions with a pH less than 7

Answer 16

more located on the left conduct electricity as they allow charge to pass through them easily basic - they neutralise acids. dissolvable metal oxides form solutions with a pH more than 7

Answer 17

inert, colourless gas they contain 8 electrons on the outer shell, meaning that they are stable

Answer 18

positive ions formed when atoms lose electrons

Answer 19

negative ions formed when atoms gain electrons

Answer 20

charged particles

Answer 21

strong, electrostatic attractions the metal atom loses electrons to form a positive ion (cation) the non metal atom gains electrons to form a negative ion (anion)

Answer 22

ions are held together in a closely packed 3d lattice arrangement by the attraction between oppositely charged ions electrostatic attraction is supa strong high melting + boiling point due to the high amount of energy to overcome the attraction can conduct electricity only when melted/dissolved

Answer 23

these bonds are formed through sharing pairs of electrons with other atoms strong electrostatic attraction between the negatively charged shared electrons and the positively charged nuclei of the atoms involved

Answer 24

strong covalent bonds which lead to weak intermolecular forces low melting and boiling points

Answer 25

dont conduct electricity except graphite insoluble bonded with strong covalent bonds requires a lot of energy to break the bonds due to the number of them, meaning a high melting+boiling point

Answer 26

made up of a network of carbon atoms that form four covalent bonds these strong covalent bonds take lots of energy to break, so diamond has a high melting point holds it in a rigid lattice structure, making diamond hard does not conduct electricity because there is no free electrons or ions

Answer 27

simple molecular substance shaped as a hollow sphere made up of 60 carbon atoms held together by intermolecular forces so they slide over each other. this makes it soft has one delocalised electron that cant move, making it a poor conductor of electricity

Answer 28

forms three covalent bonds, creating layers of carbon atoms held weakly by intermolecular forces, so the layers slide over each other. this makes it soft and slippy high melting point due to strong covalent bonds delocalised electron that is free to move. this means it can conduct electricity

Answer 29

all the relative atomic masses of the elements it contains added together

Answer 30

mass = mr x mol

Answer 31

using the provided Ar, calculate the Mr of the reactant and the products calculate the number of mols of the substance that has a mass provided look at the ratio of the moles in the equation calculate the mass using the ratio of the mols

Answer 32

actual yield (g) / theoretical yield (g) x 100

Answer 33

a reaction may not go to completion some product may be lost during transfer or purification. side reactions can occur, forming byproducts. reactants may not be pure. reactions may be reversible.

Answer 34

smallest whole number ratio of atoms in a compounds

Answer 35

find the mols of each element by dividing each mass by the relative atomic mass for that particular element divide those numbers by the smallest number of mols, creating a ratio

Answer 36

get a crucible and heat until its red hot. this ensures that it is clean with 0 traces of oil or water leave the crucible to cool then weigh it along with the lid add some clean magnesium ribbon to the crucible. reweigh the crucible, lid and magnesium ribbon heat the crucible containing the magnesium. put the lid to stop bits of solid from escaping, but leave a small gap enabling oxygen to enter the crucible for 10 minutes, or until the ribbon turns white allow the crucible to cool and reweigh with the lid and contents. find the mass by taking this away from the mass of the initial lid and crucible

Answer 37

place a rubber bung with a hole in the middle into a test tube with a small hole in the end and weigh them using a mass balance take the bung out of the test tube and spread out a small amount of copper (II) oxide in the middle of the tube reinsert the bung and weigh the test tube again. expel the air from the test tube by gently turning on the gas. after like 5 seconds light the gas by holding a burning splint next to the hole in the end of the test tube. you can control the size of the flame by changing the amount of gas thats flowing through the test tube use a bunsen burner to heat the copper (II) oxide for about 10 minutes (or until the black turns into a brownish pink colour) turn off the bunsen burner and leave it to cool weight the test tube with the bung and its contents

Answer 38

when a salt doesnt contain any water of crystallisation

Answer 39

when salt contains water of crystallisation

Answer 40

work out the mass of both substances by subtracting the crucible mass calculate the number of mols of water lost by taking away the anhydrous mass of the hydrated one + calculating the mols calculate the number of mols anhydrous salt has made work out the ratio of anhydrous salt to mols of water x has to be a whole number meaning that some errors are expected in an experiment. round it to the nearest whole number

Answer 41

flow of electrons or ions

Answer 42

where metals have a giant structure of positive ions surrounded by delocalised electrons

Answer 43

the layers of ions in a metal can slide over each other, making metals malleable - this means that they can be hammered or rolled into flat sheets

Answer 44

generally they cant conduct electricity because the ions cant move around when ionic compounds are dissolved /molten the ions separate and are able to move + conduct electricity

Answer 45

metals contain delocalised electrons, meaning that they are free to move through the structure because they can move, this also provides as efficient means of energy transfer, making metals a good conductor

Answer 46

concentration (mol/dm^3) = number of mols (mol) / volume of solution (dm^3)

Answer 47

work out the relative formula mass + mols/dm^3 of the chemical find the mass to find out the g/dm^3!!!

Answer 48

one mol of any gas always occupies 24dm^3 at room temperature and pressure (RTP)

Answer 49

room temperature = 20°C pressure = 1 atmosphere

Answer 50

moles of gas x 24

Answer 51

write out the balanced formula work out the relative formula mass of the substance with the provided mass + then calculate the moles look at the ratio of the moles in the equation calculate the volume using the ratio of the mols + formula for volume

Answer 52

the breaking down of substances using electricity

Answer 53

a molten/dissolved ionic compound

Answer 54

the positive ions (cations) in the electrolyte move towards the cathode (negative electrode) and are reduced the negative ions (anions) in the electrolyte move towards the anode (positive electrode) and are oxidised as the ions gain/lose electrons they form the uncharged substances and are discharged from the electrolyte

Answer 55

show how electrons are transferred during reactions put one of the things being oxidised/reduced on one side of an arrow, and the thing it gets oxidised/reduced to on the other balance up the number of atoms like a normal equation add the electrons to balance out the charges

Answer 56

they can be electrolysed due to the ions being free to move + are usually broken up into their elements

Answer 57

the positive Pb+2 ions are attracted to the negative cathode. at the cathode, a lead ion accepts 2 electrons and is reduced to a lead atom (Pb^2+ + 2e- -> Pb) the negative Br- ions are attracted to the positive anode. at the anode, a bromine ion loses 1 electron and is oxidised to a bromide molecule (2Br- -> Br2 + 2e-) the electrodes are made of an inert material so they dont take part in the reaction

Answer 58

they are circuits made up of the anode, cathode, electrolyte, a power source and the wires that connect the two electrodes

Answer 59

get two inert electrodes, e.g graphite or platinum clean the surface of the electrodes using sandpaper + from now on, handle them with care to avoid transferring grease onto the strips place both electrodes into a beaker filled with your electrolyte connect the electrodes to a power supply using crocodile clips and wires when you turn the power supply on, a current will flow through the cell

Answer 60

in aqueous solutions, as well as the ions from the ionic compound, there will be hydrogen ions and hydroxide ions from the water at the cathode, if H+ ions and metal ions are present, hydrogen gas will be produced if the metal is more reactive than hydrogen (e.g sodium). if not (e.g copper + silver), then a solid layer of the pure metal will be produced instead at the anode, if OH- and halide ions (Cl-, Br-, I-) are present, molecules of chlorine, bromine or iodine will be formed. if no halide ions are present, then oxygen is formed instead

topic 1: principles of chemistry Flashcards

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