Which of the following substances are mixtures? (a) tap water (b) brass (an alloy of copper and zinc) (c) concrete (d) aluminium (e) Coca cola (f) distilled water
In the following table, tick whether each of the substances listed is a mixture or a pure substance. If it is a mixture, also say whether it is a homogeneous or heterogeneous mixture.
Substance Mixture or pure Homogeneous or heterogeneous mixture ﬁzzy cold drink steel oxygen iron ﬁlings smoke limestone (CaCO3)
In each of the following cases, say whether the substance is an element, a mixture or a compound. (a) Cu (b) iron and sulfur (c) Al (d) H2SO4 (e)
The formula for calcium carbonate is CaCO3. (a) Is calcium carbonate a mixture or a compound? Give a reason for your answer. (b) What is the ratio of Ca:C:O atoms in the formula?
Give the name of each of the following substances. (a) KBr (b) HCl (c) KMnO4 (d) NO2 (e) NH4OH (f) Na2SO4 3. Give the chemical formula for each of the following compounds. (a) potassium nitrate (b) sodium iodide (c) barium sulphate (d) nitrogen dioxide (e) sodium monosulphate
Which of the following can be classiﬁed as a mixture: (a) sugar (b). table salt (c) air (d) Iron
An element can be deﬁned as: (a) A substance that cannot be separated into two or more substances by ordinary chemical (or physical) means (b) A substance with constant composition (c) A substance that contains two or more substances, in deﬁnite proportion by weight (d) A uniform substance
Classify each of the following substances as an element, a compound, a solution(homogeneous mixture), or a heterogeneous mixture: salt, pure water, soil, salt water, pure air, carbon dioxide, gold and bronze
Given the following descriptions, write the chemical formula for each of the following substances: (a) silver metal (b) a compound that contains only potassium and bromine (c) a gas that contains the elements carbon and oxygen in a ratio of 1:2
Give the names of each of the following compounds: (a) NaBr (b) BaSO4 (c) SO2
For each of the following materials, say what properties of the material make it important in carrying out its particular function. (a) tar on roads (b) iron burglar bars (c) plastic furniture (d) metal jewellery (e) clay for building (f )cotton clothing
In each of the following, say whether the chemical substance is made up of single atoms, simple molecules or giant molecules. (a) ammonia gas (NH3) (b) zinc metal (Zn) (c) graphite (C) (d) nitric acid (HNO3) (e) neon gas (Ne2)
Represent each of the following molecules using its chemical formula, structural formula and ball and stick model. (a) H2 (b) NH3 (c) sulfur dioxide
Which of the following atoms has 7 electrons? (a) 25 He(b) 13 6 C (c) 7 3Li (d) 15 7 N
A gas of unknown volume has a temperature of 14◦C. When the temperature of the gas is increased to 100◦C, the volume is found to be 5.5 L. What was the initial volume of the gas?
A gas has an initial volume of 2600 mL and a temperature of 350 K. (a) If the volume is reduced to 1500 mL, what will the temperature of the gas be in Kelvin? (b) Has the temperature increased or decreased? (c) Explain this change, using the kinetic theory of matter.
An unknown gas has an initial pressure of 150 kPa and a volume of 1 L. If the volume is increased to 1.5 L, what will the pressure now be?
A bicycle pump contains 250 cm3 of air at a pressure of 90 kPa. If the air is compressed, the volume is reduced to 200 cm3. What is the pressure of the air inside the pump?
The air inside a syringe occupies a volume of 10 cm3 and exerts a pressure of 100 kPa. If the end of the syringe is sealed and the plunger is pushed down, the pressure increases to 120 kPa. What is the volume of the air in the syringe?