Introduction to Chemistry Chapter 1 Lesson 3 Measuring Matter Introduction to Chemistry Chapter 1 Lesson 3

Field Trip Travel to the eastern coast of Africa and you will find the country of Djibouti. There, you can visit one of the saltiest bodies of water in the world. Lake Assal is ten times saltier than the ocean. Its crystal white beaches are made up of salt. While on your visit to Lake Assal, be sure to take a dip in the clear blue waters. Take a book or magazine with you to read. Wait, what? Take a book into a lake? It might seem strange, but bodies of water with high salt contents, like Lake Assal or the Dead Sea in the Middle East, allow you to float so well that it's nearly impossible to sink below the surface of the water. Salt water is denser than fresh water. Less-dense liquids float on top of more-dense liquids. You, too, will float on top of the salty water. In fact, it will be difficult even to swim, so what else can you do? Read a book while you float along!

Measuring Mass and Volume Weight is a measure of the force of gravity on an object. Weight varies with location in the solar system. A more massive object will exert a greater gravitational force, so the weight of an object on that more massive planet or moon will be greater. Weight is measured with a scale. Mass is the amount of matter in an object. It does not change with location. Mass is constant. For this reason, scientists prefer to describe matter in terms of mass rather than weight.

Measuring Mass and Volume To measure the properties of matter, scientists use the International System of Units, or SI. The SI unit of mass is the kilogram (kg). If a smaller unit of mass is needed, the gram (g) is used. There are 1,000 grams in a kilogram or 0.001 kilogram in a gram.

Measuring Matter Measuring Weight Use the weight of the first scale to estimate the weight of the fish on the other scales.

Measuring Matter Measuring Mass What is the mass of each object, measured in kilograms?

Measuring Mass and Volume Another measurable property of matter is volume, or the amount of space matter occupies. The SI unit of volume is the cubic meter (m3). Other common SI units of volume are the cubic centimeter (cm3), the liter (L), and the milliliter (mL). There are 1,000 milliliters in a liter or 0.001 liter in a milliliter. One milliliter is the same volume as 1 cm3. The volume of a rectangular solid is calculated according to the following formula. Volume = Length x width x height

Measuring Mass and Volume The first country to use an SI-based system of measurement was France in 1795. Today, there are only three countries in the world who have not adopted the SI system—Liberia, Myanmar, and the United States.

Measuring Matter Calculating Volume What is the volume of the suitcase?

Measuring Matter Measuring Irregular Objects One way to measure the volume of an irregular object is to submerge it in liquid in a graduated cylinder.

How Is Density Determined? Density is a measure of the mass of a material in a given volume. Density is expressed as the number of grams in one cubic centimeter, or g/cm3. Because one milliliter is the same volume as one cm3, density can also be expressed as g/mL. You can determine the density of a sample of matter by dividing its mass by its volume.

How Is Density Determined? The density of water is 1 g/mL, or 1 g/cm3. Objects with greater densities will sink. Objects with lesser densities will float. Density is a physical property of a substance. It can be used to identify an unknown substance.

Liquid Layers Apply Concepts Liquids form layers based on density. Label the layers of colored liquid in the column according to their densities. The liquids are water (1.00 g/mL), honey (1.36 g/mL), dish soap (1.03 g/mL), corn syrup (1.33 g/mL), and vegetable oil (0.91 g/mL). Calculate What is the density of a liquid with a mass of 17.4 g and a volume of 20 mL? Where would this liquid be in the column? (Use the labels from Question 1.) Challenge Using the layers from Question 1, in which layer(s) would a solid cube with 6-cm sides and a mass of 270 g float? Explain.