s3 chem Flashcards
what is the Si Unit of time?
second (s)
what is the Si Unit of temperature?
kelvin (K)
temperature in K (kelvin) = temperature in degree celcius + ?
273
what is the Si Unit of length?
metre (m)
what is the Si Unit of mass?
kilogram (kg)
what is the Si Unit of volume?
cubic metre (m^3)
1m = ?dm
10
1m^3 = ?dm^3
? = 1000
what is the degree of accuracy of a pipette?
10.0 cm ^3 or 25.0cm^3 (e.g : 10, 20, 30)
what is the degree of accuracy of a volumetric flask?
100 cm^3 or 250cm^3
what is the degree of accuracy of a measuring cylinder?
a range of volumes to the nearest 0.5cm^3 (e.g: 31.5 cm^3 or 23.0 cm^3)
what is the degree of accuracy of a burette?
a range of volumes to the nearest 0.05 cm^3. (e.g: 31.55 cm^3 or 23.00 cm^3)
what kind of apparatus can we use to measure the volume of a gas?
gas sringe
what can a magnet be used to separate in the separation of solid-solid mixtures?
a magnet can be used to separate magnetic solids from non-magnetic solids
name 3 different ways/techniques to separate solid-solid mixtures.
magnetic attraction, sieving, and suitable solvents.
how does sieving work?
in a mixture of bigger and smaller particles, we can use a sieve of the right pore size to separate the components. The pore size tells us how big the holes in the filter are. Bigger pores let bigger particles through.
- a sieve can be used to separate solids with different particle sizes
how does using suitable solvents to separate solid-solid mixtures?
a suitable solvent can be used to separate solid-solid mixtures in which only one of the solids is soluble in the solvent.
name 4 different ways/techniques to separate solid-liquid mixtures
filtration, evaporation to dryness, crystallisation, simple distillation
what is evaporation to dryness used for?
to separate a dissolved solid from its solvent by heating the mixture until all the solvent has vaporised.
what is crystallisation used for?
to obtain a pure solid from its saturated solution. (saturated solution = one in which no more solute can be dissolved.
what is simple distillation used for?
to separate a pure solvent (liquid) from a solution.
what are 2 ways/techniques to separate liquid-liquid mixtures?
chromatography, fractional distillation
what is chromatography used for?
to separate a mixture of substances which have different solubilities in a given solvent.
what is fractional distillation used for?
to separate miscible liquids with different boiling points
how can the purity of substances be determined?
a pure substance has a specific melting/boiling point under fixed conditions.
define the kinetic particle theory
all matter is made up of tiny particles and these particles are in constant random motion.
define the kinetic particle theory
all matter is made up of tiny particles and these particles are in constant random motion.
define sublimation
the process by which a solid changes directly into a gas
define an atom
an atom is the smallest particle that can still have the chemical characteristics of an element.
does the no. of protons in an atom equate to the no. of electrons in an atom?
yes
define a ion
an ion is the particle formed when an atom or group of atoms gains or loses electrons. (no. of protons and neutrons remain the same)
define a ion
an ion is the particle formed when an atom or group of atoms gains or loses electrons. (no. of protons and neutrons remain the same)
what are isotopes?
isotopes are atoms of the same element that have the same proton(atomic) number but different nucleon(mass) numbers. (diff numbers of neutrons)
what gases are monoatomic? (single atoms & chemically un-reactive)
noble gases. as the have a noble gas electronic configuration
what are positive ions?
positive ions have more protons than electrons and have a net positive charge,
what are negative ions
negative ions (anions) have a net negative charge and usually have a noble gas electronic configuration.
define ionic bonding
an ionic bond is the mutual electrostatic attraction between ions of opposite charges
what are ionic structures?
an ionic compound forming a structure called a giant ionic crystal lattice.
define covalent bonding/valency
when 2 non-metal gases share electrons to form a noble gad configuration
ionic compounds have ? melting and boiling points
high
what is the hardness of ionic compounds?
ionic compound are physically hard but brittle
what is the solubility in ionic compounds?
ionic compounds are often soluble in water but insoluble in organic solvents
when can ionic compounds conduct electricity?
ionic compounds conduct electricity when molten or in aqueous solution, but not in the solid state.
what are the usual structural properties of covalent substances at room temperature and pressure?
simple covalent substances are usually gases or liquids at room temperature and pressure.
why do simple covalent substances have low melting and boiling points?
as the molecule gets larger , the melting and boiling points are usually higher.
why do simple covalent substances have low melting and boiling points?
as the molecule gets larger , the melting and boiling points are usually higher.
what is the solubility of simple covalent substances?
simple covalent substances are usually insoluble in water and soluble in organic solvents.
what is the electrical conductivity of simple covalent substances?
simple covalent substances do not conduct electricity.
what is an alloy
an alloy is a mixture of a metal with one of more other elements.
what are the structural properties of pure metals?
pure metals are malleable and ductile.
do pure metals have high or low melting or boiling points?
pure metals have high melting and boiling points. they are good conductors of heat
do pure metals have high or low melting or boiling points?
pure metals have high melting and boiling points. they are good conductors of heat
what is the electrical conductivity of metals and alloys?
metals and alloys are good conductors of electricity
what is the relative atomic mass of an element?
the relative atomic mass of an element is the average mass of one atom of that element reletive to 1/12 the mass of an atom of carbon-12 (standard atom)
what is the relative molecular mass of a molecular substance?
the relative molecular mass of a molecular substance is the average mass of one molecule of that substance relative to 1/12 the mass of an atom of carbon-12.
what is the relative formula mass of an ionic compound?
the relative formula mass of an ionic compound is the average mass of one unit of that compound relative to 1/12 the mass of an atom of carbon-12
how do we calculate the number of moles in a gas?
volume / 24dm^3
what is a acid?
an acid is a substance that produces hydrogen ions, H+, in aqueous solutions
acids react with reacting metals to form ?
a salt and hydrogen gas
acids react with bases to form ?
a salt and water
acids react with bases to form ?
a salt and water
acids react with carbonates to form ?
a salt, water, and carbon dioxide gas
what is a base?
a base is any metal oxide or hydroxide. They can contain either the oxide ion or the hydroxide ion.
what is an alkali?
an alkali is a substance that produces hydroxide ions, OH-, in aqueous solutions
alkalis react with acids to form ?
a salt and water
name 4 properties of alkalis
- they taste bitter
- feel slippery and soapy
- dissolve in water to form solutions that can conduct electricity
- turns red litmus paper blue
what is the ionic equation for any neutralisation reaction between an acid and alkali?
H+ (aq) + OH- (aq) — Hsmall 2 O(l)
what is the ionic equation for any neutralisation reaction between an acid and alkali?
H+ (aq) + OH- (aq) — Hsmall 2 O(l)
alkalis when heated with ammonium salts, give off ?
ammonia gas
define oxidation
- gain of oxygen
- loss of hydrogen
- loss of electrons
- oxidation number/state will increase
define reduction
- loss of oxygen
- gain of hydrogen
- gain of electrons
- oxidation number/state will decrease
what is the periodic table?
a list of elements arranged in order of increasing proton(atomic) numbers
what are groups in the periodic table?
the vertical column of elements
what are periods in the periodic table?
the horizontal row of elements
the number of electron shells an element has is the same as its ?
period number
what are the metallic properties of elements across a period?
there is a decrease in metallic properties and an increase in non-metallic properties across a period.
what are the metallic properties of elements when going down a group?
going down a group, there is an increase in metallic properties and a decrease in non-metallic properties
what happens in a displacement reaction?
in a displacement reaction, on element takes the place of another element in the compound.
how are metals arranged in the reactivity series?
in the reactivity series, metals are arranged from the most reactive to the least reactive.
what are the conditions for rusting to occur
the presence of both oxygen(in air) and water are necessary for rusting to occur.
what is an acid?
substances that dissolve in water to produce H+ ions
what are strong acids?
strong acids are acids that dissolve completely when dissolved in water to produce a high concentration of H+ ions. Thus, pH of strong acids are very low
what are weak acids?
weak acids are acids that only partially dissolve in water and produce a low concentration of H+ ions. Thus, pH of weak acids are not very low
acids + metals = ?
salt + H2
acids + metals = ?
salt + H2
