Unit 1 Exam Review Lab Safety, Measurements, Scientific Method, and Density

Lab Safety

Long hair must be secured to the back of your head. A. True B. False

What things do you need to wear before beginning any laboratory exercise? A. Safety apron or a lab coat B. All of these C. Gloves D. Goggles

What should you do first if a glass breakage occurs? A. Immediately contact your teacher. B. Leave it where it is without telling anyone. C. Sweep it up & throw in trash. D. Cover it with a piece of paper.

What are the 2 most vulnerable parts of your body during lab? A. Eyes B. Nose C. Mouth D. Skin

Which of the following is the safest way to make laboratory observations of an unknown substance? a. Smell the substance by placing your nose directly above the flask b. Determine its texture by feeling the substance with your fingers c. Visually observe color and texture d. Taste the substance

What are the 2 most vulnerable parts of your body during lab? A. Eyes B. Nose C. Mouth D. Skin

MEASUREMENTS

Measuring volume of a liquid in a graduated cylinder First you must know the scale of the cylinder. In other words, how much does each line go up by.

Measuring volume of a liquid in a graduated cylinder To calculate the scale, look at two consecutive labeled lines. Take the difference between the 2 numbers. Then divide that number by how many lines it takes to get there.

Measuring volume of a liquid in a graduated cylinder So for this cylinder, take = 10. Then count the lines from 30 to 40. There are 10 lines. So, 10 divided by 10 = 1. The scale of this cylinder is 1.

Measuring volume of a liquid in a graduated cylinder Now look at the bottom of the meniscus. It is located between 36 and 37 ml. The volume of the liquid in this cylinder is about 36.5 ml.

Measuring volume of a liquid in a graduated cylinder What is the volume of liquid in this graduated cylinder? First, what is the scale of the cylinder?

Measuring volume of a liquid in a graduated cylinder The scale is 1. So, the volume of the liquid in this cylinder is 56 ml.

Measuring volume of a liquid in a graduated cylinder Now let’s try this one. What’s the scale of this graduated cylinder?

Measuring volume of a liquid in a graduated cylinder Take the difference between 2 consecutive numbers: 3 – 2 = 1. Now divide that number by the amount of lines it takes to get from 2 to 3. It takes 2 lines. So, 1 ÷ 2 = 0.5

Measuring volume of a liquid in a graduated cylinder Now let’s try this one. What’s the scale of this graduated cylinder?

Measuring volume of a liquid in a graduated cylinder 2 – 1 = 1 It takes 5 lines to get from 1 to 2. 1 ÷ 5 = 0.20 The scale is 0.20.

Measuring volume of a liquid in a graduated cylinder Now let’s try this one. What’s the scale of this graduated cylinder?

Measuring volume of a liquid in a graduated cylinder Now let’s try this one. 40 – 30 = 10 It takes 10 lines to get from 30 to ÷ 10 = 1

Reading a thermometer You determine the scale of a thermometer the same way as a graduated cylinder. What do you think the scale of this thermometer is?

Reading a thermometer 30 – 20 = 10 It takes 5 lines to get from 20 to ÷ 5 = 2 The scale is 2 degrees.

Reading a thermometer Okay, so the scale is 2 degrees. What is the temperature of the room with this thermometer?

Reading a thermometer The liquid is halfway between 30 and 32. So, the temperature is approximately 31 degrees Celsius.

Reading a triple beam balance What is the reading on this triple beam balance?

Reading a triple beam balance The 100 gram rider is set at 0. The 10 gram rider is set at 20. The 1 gram rider is set at 7.7. Add all those together and you get 27.7 grams.

Reading a triple beam balance What is the reading on this triple beam balance?

Reading a triple beam balance g

Mass of liquid in a beaker To find the mass of a liquid in a beaker. Take the difference between the mass of the liquid in a beaker and the mass of the beaker by itself.

Mass of liquid in a beaker So, – = g

Mass of liquid in a beaker The mass of the liquid and the beaker = grams The mass of the beaker alone = 58.0 grams What is the mass of the liquid?

Mass of liquid in a beaker g – 58.0 g = g

Scientific Notation What is this number in scientific notation? Because the exponent is -2, you must move the decimal to the left 2 spaces.

Scientific Notation So in scientific notation, this number is

Scientific Notation Let’s try these… x x x 10 10

Scientific Notation Let’s try these… x , x x ,900,000,000

Scientific Notation Now let’s change into scientific notation. Let’s try these… ,000, ,420,000,000,000

Scientific Notation Now let’s change into scientific notation. Let’s try these… ,000, x x ,420,000,000, x 10 13

Metric Conversions Let’s convert 15 ml to kl. We must move the decimal to the left 6 spaces kl

Metric Conversions Let’s convert! hg to mg dam to m dl to hl

Metric Conversions Let’s convert! hg to mg 34,000 mg dam to m 50.3 m dl to hl hl

Scientific Method

Scientific Method In the scientific method, scientific theories __________. a. Must be tested and verified by observations. b. Must be verified by leaders in the specific field of science c. Are absolute fact d. Must be consistent with the previous universally accepted scientific concepts

Scientific Method Which of the following means most nearly the same as the word “control” as used in describing a scientific experiment? a. A preliminary trial experiment b. An experiment with a variable factor c. A repeat experiment d. A comparison experiment

Jessica is 5 feet 3 inches tall. Observation or Inference?

Scientific Method While observation is what one sees, feels, hears, tastes, or touches, an inference is an assumption of what one has seen. Inference is only a guess that is drawn from the observation that one has made.

Density Density is a characteristic property of a substance. The density of a substance is the relationship between the mass of the substance and how much space it takes up (volume). The mass of atoms, their size, and how they are arranged determine the density of a substance. Density equals the mass of the substance divided by its volume; D = m/v. Objects with the same volume but different mass have different densities.

Density When you squeeze an object, the pressure on it ______________ (increases, decreases, does not change). What does increasing the pressure do to the volume of the object? _____________ (increases, decreases, does not change)

Density What does increasing the pressure do to the mass in an object? _________________ (increases, decreases, does not change) What does increasing the pressure do to the density of the object? _____________ (increases, decreases, does not change)

Density If the mass is 35g and the volume is 7cm 3, what is the density of the object? A. 135 g/cm 3 B. 5 g/cm 3 C g/cm 3 D cm 3

Density Calculate the mass of a liquid with a density of 3.2 g/mL and a volume of 25 mL. 80 grams

When the Earth first formed, it was a very hot mixture of liquid materials. As it cooled, these liquids formed layers inside the Earth. Using what you know about density, explain why the crust of the Earth (the outermost layer) is the least dense layer of the Earth.

Density If something is less dense than the substance it is in, it will float. If it is more dense, it will sink down. Following this logic, is the inner core (center) of the Earth more or less dense than the crust (outer part) of the Earth?