Chemistry Study Guide: Test #1. A hypothesis is best described as: An educated guess If …….then…….. The scientific method is: A systematic approach to.

Chemistry Study Guide: Test #1

A hypothesis is best described as:

An educated guess

If …….then……..

The scientific method is:

A systematic approach to answer a question - testable

A scientific theory is best described as:

An explanation supported by many experiments

The dependent variable is best described as:

The one that changes; located on the Y axis

In an experiment, the independent variable is the one that:

“I” can control; located on the X axis

The best way to find the volume of a marker is called:

Water displacement

The formula for density is:

D = m/v

In determining how many significant figures a number has, you must first look for a

decimal

If a decimal is present, then you start counting from the front (left)

If a decimal is absent, then you start counting from the back (right)

PacificAtlantic

The first rule of lab safety is: Tell the teacher

Volume is measured in mL or cm3, which are the same

Density is written in which units? g/mL or g/cm3

When measuring irregular objects (such as cylinders, marbles, rocks) you should use water displacement as the method of finding volume.

You can only use the L*W*H method of finding volume when objects are considered regular in shape or easily measured with a ruler.

Metric Measurements

Kilo Hecto Deca m deci centi milli 1000 100 10 L 10 100 1000

g

Kids have dropped over dead converting metric

Which prefix means 1,000? Kilo

Which prefix means 1/100? centi

Which prefix means 1/1000? milli

Read the following graduated cylinders. Make sure to include (mL) in your answer

52.9 mL

6.64 mL20.6 mL

Descriptor Qualitative or Quantitative

Red Qualitative

17 centimeters Quantitative

46 desks Quantitative

Rusty Qualitative

48 marbles Quantitative

152 milliliters Quantitative

Smelly Qualitative

Calculate the densities of the following objects. Remember to place units after each

number.

Object A:

Length = 6 cm

Width = 3 cm

Height = 1 cm

Mass = 36 g

Volume = 18 cm3

Density = 2 g/cm3

Object B:

Length = 10 cm

Width = 5 cm

Height = 2 cm

Mass = 300 g

Volume = 100 cm3

Density = 3 g/cm3

Object C:

Use the water displacement method to determine the density of Object C (silly putty)

Initial water level in graduated cylinder =

25 mL

Water level after placing silly putty into graduated cylinder = 29 mL

Mass of silly putty = 8g

Volume = 4 mL

Density = 2 /mL

Which of the following materials will float on water (density = 1.00 g/cm3)?

Corn oil = .93 g/cm3 -- float

Glycerine = 1.26 g/cm3 -- sink

Corn syrup = 1.38 g/cm3 -- sink

Wood = .85 g/cm3 -- float

Steel = 7.81 g/cm3 -- sink

Rubber = 1.34 g/cm3 -- sink

Ice = .92 g/cm3 -- float

Water = 1.00 g/cm3 -- neither

Round the following to 3 significant figures

124.78 125

1.001 1.00

56.0 56.0

78.490 78.5

175.689 176

Complete the following calculationsbe sure to use the proper number of significant

figures

51.8 kg + 65.23 kg = 117 Kg

16 m x 31 m x 0.003 m = 1.488 1 m3

3.45 m ∕ 2.1 s = 1.6 m/s

45.21 x 3.0 = 136.63 140____

12.01 g - 6.0 g = 6.01 6.0 g

Describe each of the following as:accurate – precise – both - none

NonePrecise

BOTH None