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CHEMISTRY 11 – CLASSIFICATION OF MATTER WORKSHEET 1) A clear glass bottle contains white sand, some nails, salt water with some dye dissolved in it, and a layer of gasoline on top. How many phases are present in this system (excluding the bottle and lid)? Four phases are mentioned: (1) white sand, (2) nails, (3) salt water with some dye dissolved in it and (4) the layer of gasoline. A 5th phase (the air) could be included since it would be above the glass bottle containing the substances, however it is not mentioned as being part of the system. 2) What should you see if a system is (a) heterogeneous? (b) homogeneous? (a) a heterogeneous system would contain visible boundaries separating one phase from another (b) a homogeneous system would have everything looking the same no matter which part of the system is being examined 3) Classify each of the following as one of heterogeneous or homogeneous. (a) a diamond (b) a tree (c) a hen’s egg (d) a cup of coffee (apart from the cup) (a) homogeneous (b) heterogeneous (c) heterogeneous (d) homogeneous 4) Assume you have a 10 g piece of pure gold. Should you refer to the gold as an atom or an element? 10 g of gold would be referred to as an element since the term “atom” is used to describe the smallest possible particle of gold, and a 10 g piece of gold could be subdivided into smaller pieces. 5) In what way are a solution and a compound similar? In what way do they differ? A solution and a compound are similar since there are homogeneous, but they are different since a compound is a pure substance while a solution is made of two or more pure substances. 6) Classify the following materials as element, compound, pure substance, homogeneous mixture or heterogeneous mixture – there may be more than one answer for each. (a) A clear liquid which can be boiled away to leave a white solid homogeneous mixture (b) CH3OH in H2O homogeneous mixture (c) A collection of solid particles, some of which are white and some of which are red heterogeneous mixture (d) Air homogeneous mixture (e) A solid which melts at 170°C element, compound, or homogeneous mixture (f) Dirt heterogeneous mixture (g) A gas pure substance, homogeneous mixture (h) Baking soda (NaHCO3) compound (i) A brown liquid that is separable into simpler substances by physical means homogeneous mixture (j) A clear liquid that does not separate into simpler substances with gentle heating – it only evaporates. When an electric current is used on it, two gases are produced. compound (k) A liquid element, compound, homogeneous mixture (l) A pink gas that has a fixed percentage composition and is not separable into simpler substances by physical means or any chemical reaction. element (m) Glucose (C6H12O6) compound (n) A brown gas that has a fixed percentage composition and is separable into simpler substances by means of a chemical reaction, but not by any physical means. compound (o) Soda pop heterogeneous mixture (p) A brown and white solid that is separable into simpler substances by putting the material in water. The brown part sinks while the white part floats. heterogeneous mixture (q) Green dye that separates into blue and yellow dye. homogeneous mixture (r) A green liquid that will separate into two distinct layers if left unattended for a period of time. homogeneous mixture (s) A liquid that boils away completely at 136°C. When the liquid is strongly heated in a closed container, a yellow gas and a black solid are produced. compound 7) Which substance is the solute in each of the following? (a) water containing 5% acetic acid (this mixture is commonly called “vinegar”) acetic acid (b) tincture of iodine (a small amount of solid iodine mixed with alcohol) iodine (c) a mixture containing 60% alcohol and 40% chloroform chloroform (d) a solution containing 900 g of silver nitrate and 100 g of water silver nitrate (water is always the solvent, if present) 8) Which of sugar, dirt and air are pure substances and which are mixtures? Sugar is a pure substance while the dirt and air are mixtures 9) Is it easier to prove that an unknown substance is an element or a compound? Explain. A compound would be easier to prove since it’s easy to demonstrate that you can decompose (break apart) a substance but it’s difficult to prove that you can’t. 10) Why is no material truly homogeneous at the atomic level? Atoms are not homogeneous (the same throughout) at the atomic level since they are made up of smaller particles (electrons, protons, neutrons) and therefore nothing composed of atoms is truly homogeneous.