Lesson 2 Chemistry Basics Continued Quiz

When completing the following conversion using dimensional analysis, what would the conversion factor look like in the set up? 36 inches to cm. (1 ft)/(12 in) 1 in)/(2.54 cm) (2.54 cm)/(1 in) (12 in)/(1 ft)

(2.54 cm)/(1 in)

Your friend is having a hard time with the terminology in this unit. He is confused between the terms pure substances, mixtures, elements, compounds, homogeneous, and heterogeneous, as well as the difference between physical and chemical changes. Without just reciting the definitions, explain each term to your friend and provide at least two examples of each that will help him understand the concepts better.

-A pure substance can be an element or a compound. It is only one kind of particle and it can be fixed or have a constant structure. Two examples of pure substances are ammonia and a diamond. An element is a chemical made up of only one atom. It can be any substance that is located on the periodic table. Elements cannot be broken down into other substances. 2 examples of elements found on the table of elements are gold (AU) and oxygen (O). A compound is made of 2 or more different elements that are chemically bonded together. A compound (combined elements) can be broken down into respective elements. One example of a compound is that water (H2O) is made up of 2 hydrogen atoms and 1 oxygen atom. Another example would be that carbon dioxide (CO2) is made up of 1 carbon atom and 2 oxygen atoms. A mixture is made by mixing 2 or more substances that are not related (they are not chemically bonded.) An example of a mixture is dirt and water which form mud. Another example would be potassium nitrate, sulfur, and carbon which creates gun powder. Homogeneous mixtures are composed of parts or elements that are the same kind (alike.) Examples of homogeneous mixtures are lotion and orange juice because you cannot see the different parts that create the mixtures.) Heterogeneous mixtures are composed of parts or elements that are not the same. Examples of heterogeneous mixtures are Rocky Road Ice Cream and Vinegar dressing. A physical change is any change that occurs to a substance that affects its physical properties. 2 examples would be boiling water and tearing a sheet of paper. A chemical change is any change that happens to a substance that affects its chemical properties. 2 examples would be cooking an egg and heating sugar to create caramel. The difference between a chemical change and a physical change is that chemical changes involve the production of a new substance by breaking and regrouping atoms. Physical changes are able to be reversed and don't require different compounds or elements.

A metal cube is found in your lunchroom and you and your colleagues want to know what metal it is. Describe a process that could be used to determine what metal a metal cube is made up of. Remember that you have a table of common densities for metals in Lesson 2. Make sure to explain how and what measurements you will make (highlighting the importance of making measurements to the correct degree of certainty). Also include the mathematical process that you follow to carry out these experiments. Be sure to include proper units in your explanation.

-You can identify a metal by measuring its density and comparing your result to a list of known densities. Density is a ratio and it needs to be calculated from measurements of mass and volume ( Density = mass/volume.) You can determine the mass of an unknown metal by using a balance or scale. Since this object is a cube, measurements of length, width, and height can be made. The volume will be calculated by using the formula volume = length x width x height. In addition, you can determine the volume of irregular shaped objects by using the method of water displacement. You drop the object into a graduated cylinder containing a known volume of water and measuring the new volume. Then, you will divide the mass by the volume and compare it to the density to densities that are known. The density formula (density = mass/volume) can be used in calculations. You can always find the density if you do know the mass and volume. Likewise, you can also find the mass if you know the density and volume. You need 2 variables of the 3 variables to find the amount of the other variable.

What is the volume of an object that has a mass of 3.4 g and a density of 2.4 g/mL? A) 1.4 mL B) 0.71 mL C) 710 L D) 14 mL

1.4 mL

How many joules are in 56.3 cal? A) 236 J. B) 253.56 J. C) 13.456 J. D) 13.4 J.

236 J.

Convert 9.3 kg to centigrams. A) 930,000 cg B) 0.000093 cg C) 9300. cg D) 0.0093 cg

A) 930,000 cg

Which of the following is a correct conversion between °C and K? A) 333°C = 60 K B) -215°C = 58 K C) 733°C = -200 K D) 100°C = 173 K

B ) -215°C = 58 K

What is the density of an object that has a volume of 4.5 L and a mass of 54.0 g? A) 0.083 g/L B) 12 g/L C) 12 g/mL D) 83 g/L

B) 12 g/L

Convert 75°F to °C. 22°C 24°C 26°C 28°C

B) 24°C

How many calories are in 349 J? A) 1460 cal. B) 84.413 cal. C) 83.4 cal. D) 1460.2 cal.

B) 83.4 cal.

Which of the following is not simply a change in state? A) melting. B) burning. C) freezing. D) subliming.

B) burning.

Pure substances include: A) elements only. B) elements and compounds. C) compounds and mixtures. D) all matter.

B) elements and compounds.

The Law of Conservation of Energy is a statement that A) energy must be conserved, and you are breaking the law if you waste energy. B) energy cannot be created nor destroyed, just transferred C) energy cannot be used up faster than it is created. D) the supply of energy is limited so we must conserve it.

B) energy cannot be created nor destroyed, just transferred

Molecules in this state of matter completely fill the container they are in. A) solid. B) liquid. C) gas.

C) gas.

Which of the following is an element? Sodium Chloride water ammonia arsenic

arsenic

Which of the following is a homogeneous mixture? A) sand. B) rocky road ice cream. C) pizza. D) eye drops.

eye drops.

What kind of energy is carried by objects in motion? A) kinetic energy. B) electrical energy. C) radiant energy. D) chemical energy.

kinetic energy.