C165 - Unit 3 Chemistry - Lessons 7-19: Quiz

Review the periodic table. Which of the following elements is a metalloid? Oxygen (O) Argon (Ar) Hydrogen (H) Arsenic (As)

Arsenic (As) Explanation: Arsenic (As) is a metalloid.

When NaCl forms, each Na atom transfers an electron to a Cl atom. When this occurs, the Na and Cl atoms become ions. Each Na ion has a charge of: -2 +2 -1 0 +1

+1 Explanation: Each sodium atom loses one electron, producing an overall charge of +1.

An ice cube has a mass of 100 g. How much liquid water is present when the ice cube melts? Less than 100g 100 g More than 100 g

100 g Explanation: Because of the law of conservation of matter, mass is not gained or lost during a phase change.

Aluminum (Al) and chlorine (Cl2) can react to form aluminum chloride (AlCl3) according to the following balanced chemical equation: 2Al+3Cl2→2AlCl3 If 10 g of aluminum reacts with 39 g of chlorine, how many grams of aluminum chloride will form? 39 g 29 g 49 g 10 g

49 g Explanation: Mass is conserved in a chemical reaction, and 10 + 39 = 49

Use the periodic table to answer the following question. Which period is molybdenum (Mo) in? 5 4 6 3

5 Explanation: Molybdenum (mo) is in the fifth row, which is period 5.

How does a physical change differ from a chemical change? A chemical change produces new substances. A chemical change involves water. A chemical change involves chemicals such as sodium chloride. A chemical change can reduce or increase the amount of matter.

A chemical change produces new substances. Explanation: A chemical change changes the identity of substances involved by rearranging which atom is bonded to which.

Which of the following is a chemical change? Hot wax is poured into a candle mold Rocks become smooth when they tumble in the surf A metal bridge turns brown as it rusts Water evaporates off a hot stovetop

A metal bridge turns brown as it rusts Explanation: Rust is a new compound that forms from a chemical reaction between iron and oxygen.

Use the periodic table to answer the following question. Which of these elements has properties most similar to those of strontium (Sr)? Yttrium (Y) Rubidium (Rb) Scandium (Sc) Calcium (Ca)

Calcium (Ca) Explanation: Calcium is in the same column as strontium, which means that these two elements are in the same family.

Use the periodic table to answer this question. Which of the following elements are metals? Calcium (Ca), radon (Rn), and manganese (Mn) are all metals. Calcium (Ca), aluminum (Al), and manganese (Mn) are all metals. Calcium (Ca), aluminum (Al), and antimony (Sb) are all metals. Calcium (Ca), aluminum (Al), and hydrogen (H) are all metals.

Calcium (Ca), aluminum (Al), and manganese (Mn) are all metals. Explanation: Calcium (Ca), aluminum (Al), and manganese (Mn) are all metals.

Which type of bond forms when electrons are shared? Ionic bond Covalent bond

Covalent bond Explanation: A covalent bond forms when electrons are shared.

Cu+1 is an ion of copper with a charge of plus one. If Cu+1 loses an electron, what will be formed? Cu+2 Ni+1 Cu Zn+1

Cu+2 Explanation: If Cu+1 loses one electron, the positive charge of the ion will increase by one

What happens to the electrons when a metallic bond is formed? Electrons are shared between two atoms. Electrons are transferred from one atom to another. Electrons float free in an electron sea. Electrons float away.

Electrons float free in an electron sea. Explanation: In a metallic bond, electrons float free in an electron sea.

Two molecules of hydrogen peroxide (H2O2) react to form two molecules of water (H2O) and one molecule of oxygen (O2) according to the following balanced chemical equation: 2H2O2→2H2O+O2 Which substances are reactants in this reaction? H2O2 is the only reactant. H2O and O2 are both reactants H2O2, H2O, and O2 are all reactants. 2H2O2 and H2O are both reactants.

H2O2 is the only reactant. Explanation: Reactants are shown on the left side of a chemical equation.

When shaking salt from a salt shaker, you see that the salt, which is sodium chloride (NaCl), is in the form of many small crystals. What holds the Na particles and Cl particles in place inside the crystals? Covalent bonds between the chlorine atoms Metallic bonds between the atoms of sodium metal Ionic bonds between sodium and chlorine Covalent bonds between sodium and chlorine

Ionic bonds between sodium and chlorine Explanation: The opposite electrical charges of the Na+ and Cl- ions produce a force of attraction, which is an ionic bond.

Which statement is true about chemical and physical changes? Matter is conserved in chemical changes but not physical changes. Matter is conserved in physical changes but not chemical changes. Matter is not conserved during any type of change. Matter is conserved in both chemical and physical changes.

Matter is conserved in both chemical and physical changes. Explanation: Matter is conserved when chemical or physical changes occur

Which of the following processes results in an increase in the motion and kinetic energy of particles? Evaporation and freezing Condensation and freezing Melting and condensation Melting and evaporation

Melting and evaporation Explanation: Melting and evaporation both result in an increase in the motion and kinetic energy of particles.

You conduct experiments on a sample of an unknown element and find that it is shiny, malleable, ductile, and conducts electricity well. In which of the following categories does this element MOST LIKELY belong? Nonmetal Metal Metalloid Noble gas

Metal Explanation: Metals are shiny, malleable, ductile, and conduct electricity well.

Bronze is an alloy of copper and tin. Which type of bond holds bronze together? Covalent bond Ionic bond Metallic bond

Metallic bond Explanation: Metals are held together by a metallic bond.

Which of the following statements about metalloids is true? Metalloids are shiny and have low conductivity. Metalloids are shiny and have intermediate conductivity. Metalloids are shiny and have high conductivity. Metalloids are dull and have intermediate conductivity.

Metalloids are shiny and have intermediate conductivity. Explanation: Metalloids are shiny and have intermediate conductivity.

Two atoms of nitrogen bond together to form N2. What type of chemical is N2? N2 is a compound. N2 is a mixture. N2 is an element.

N2 is an element. Explanation: N2;contains only one type of atom, so it is an element.

Review the periodic table. Which compound would be MOST chemically similar to sodium chloride (NaCl)? Aluminum chloride (AlCl3) Calcium chloride (CaCl2) Potassium chloride (KCl) Silver chloride (AgCl)

Potassium chloride (KCl) Explanation: Potassium is in the same group as sodium and has similar properties as a result of having the same number of valence electrons.

Which of these is true about a chemical change? The mass of the substances present changes. The same molecules are present before and after the change. New atoms are created and old ones destroyed. The change rearranges which atoms are bonded to which.

The change rearranges which atoms are bonded to which. Explanation: Atoms rearrange to form new chemical substances, but their atomic numbers and therefore their identities do not change.

Cooking spray contains cooking oil in a spray can. The spray can also contains a propellant. The propellant is a substance that is a gas at room temperature under normal atmospheric pressure, but exists as a liquid when its molecules are pushed together at high pressure inside the can. The liquid propellant mixes with the oil in the can. When you release the valve on top of the can, the mixture is pushed out. The sudden decrease in pressure allows the dissolved propellant liquid to change back into a gas, helping to spray a mist of oil droplets onto the cookware. You happen to notice that the spray from the nozzle feels colder than the can was before being used. Why would this happen? The mixture inside the can releases thermal energy to its surroundings. The molecules of the liquid propellant lose energy to the oil droplets. The process of compressing the gas inside the container already cooled it. The liquid propellant inside absorbs thermal energy from its surroundings as it changes into a gas.

The liquid propellant inside absorbs thermal energy from its surroundings as it changes into a gas. Explanation: When the liquid propellant evaporates to form a gas, it absorbs thermal energy.

The temperature increases as the result of the following chemical reaction: A + B → C What happens to the motion and kinetic energy of particles of matter? The motion and kinetic energy of particles decreases. The motion and kinetic energy of particles increases.

The motion and kinetic energy of particles increases. Explanation: The motion and kinetic energy of particles increases with temperature.

An inflated balloon expands when placed in the hot sun. Why? The heat creates new matter. A chemical reaction occurs that causes the matter to take up more space. More air was added to the balloon. The particles of matter in the balloon spread out more, which increases the size of the balloon.

The particles of matter in the balloon spread out more, which increases the size of the balloon. Explanation: The particles of matter in the balloon spread out more, which increases the size of the balloon.

Wearing damp clothes can make you feel cold. Why? The water has a lower temperature than the surrounding air. The water evaporates, a process that absorbs heat from your body. The water condenses, a process that absorbs heat from your body.

The water evaporates, a process that absorbs heat from your body. Explanation: As the water evaporates, it carries heat away from your body.

The fuel in a lighter is butane. When butane burns, the following change takes place. 2C4H10 + 13O2→8CO2+ 10H2O Is this a chemical change or a physical change? This is a physical change. This is a chemical change.

This is a chemical change. Explanation: A change that results in atoms being rearranged is a chemical change.

Salt dissolves in water to form saltwater. Is this considered a chemical change or a physical change? This is a chemical change. This is a physical change.

This is a physical change. Explanation: No change in chemical bonding occurs when a mixture forms. Formation of a mixture is always a physical change.

If a liquid evaporates below its boiling temperature to change into a gas by evaporation, it _____ thermal energy from its surroundings. releases neither absorbs nor releases absorbs

absorbs Explanation: The liquid absorbs thermal energy that goes into breaking its particles free from the liquid phase.

After analyzing different eggs you conclude that egg whites each have about 50 mg of sulfur in them. Based on the relative mass of iron and sulfur atoms, you conclude that the 50 mg of sulfur can react with 92 mg of iron to form FeS. 50 mg of sulfur (S) can react completely with 92 g of iron (Fe) to produce FeS. The equation describing the change that makes eggs sometimes look greenish is: S + Fe → FeS To determine the mass of FeS produced, you should __________. take into account the relative mass of the sulfur and iron atoms add the 50 mg for the S to the 92 mg for the Fe take the amount of FeS to be 50 mg take the amount of FeS to be 92 mg subtract the 50 mg for the S from 92 mg for the Fe

add the 50 mg for the S to the 92 mg for the Fe Explanation: The total mass before the reaction is the same as the mass present after the reaction.

Instructions: Use the following scenario for questions 2 and 3. Scenario: The chef places cold water in a pot, places the pot on the stove, and monitors its temperature as time passes. Which of these BEST describes the changes the chef sees occurring at different stages of heating the pot of water? Before the water begins to boil, thermal energy _____. remains the same. increases. decreases.

increases. Explanation: Thermal energy increases as the water gets hotter.

While the water boils, the average kinetic energy of the water molecules ______ remains the same. decreases. increases.

remains the same. Explanation: The added energy is going into changing the water from a liquid to a gas by breaking the attachments of the water molecules to each other, rather than into raising its temperature or average kinetic energy per molecule.