Chemical Reactions & Force and Motion

Chemical Reactions & Force and Motion

Chemical Changes/Reactions

Chemical reactions, or changes, often result in changes easily observed and new substances being formed. 

Evidence of chemical reactions includes 

energy changes such as a gain or loss 

of heat (temperature changes), the 

production of light, formation of a 

precipitate, color changes, and gas production (bubbles forming).

Multiple Choice

Which of the following would indicate a new substance has been formed?

• A solid becomes a liquid

• Powder dissolves in water

• Bubbling and fizzing occur

• A puddle of water evaporates

Multiple Choice

A solid consisting of clear crystals is combined with a blue liquid in a container, and the following observations are obtained:

-The color of a liquid change from blue to yellow

-The solid got smaller

-The solution temperature change from 25°C to 30°C

-Bubbles formed in the container

How many of the listed observations indicate a new substance was formed?

• 1

• 2

• 3

• 4

Multiple Choice

When vinegar and baking soda are combined, bubbles begin to form. Bubbles are evidence of a chemical reaction because they

• Pop when they are touched

• show that gas is forming

• Four minute fast rate

• Are generally transparent

Physical and Chemical Changes

A chemical change/reaction means that a new substance has been formed.

Multiple Choice

A physical change occurs in the digestive system when

• Gastric juices in the stomach convert proteins into amino acids

• Saliva changes complex carbohydrates into simple sugars

• Teeth break down and grind food particles into smaller pieces

• Pancreatic enzymes change fats into fatty acids and glycerol

Multiple Choice

Evidence of a chemical reaction includes anything that shows

• A new substance has been formed

• A solid has dissolved into a liquid

• The interaction between two gases

• A change in the state of matter

Chemical Formulas

Chemical Formulas

Chemical Formulas

Multiple Choice

A model of a chemical compound is shown. What is the correct way to write the formula for this compound?

• 2HO

• 2H2O

• H2O2

• HO2

Multiple Choice

A chemical formula is provided. How many atoms of hydrogen (H) are found in this substance?

• 2

• 4

• 6

• 8

Multiple Choice

A chemical formula for certain substance is shown here.

Be³Al²(SiO³)⁶

How many different elements are present in the substance represented by the chemical formula shown?

• 4

• 7

• 15

• 29

Multiple Choice

In a chemical formula what is used to indicate the number of atoms of each element

• Atomic number

• Subscript

• Coefficient

• Atomic mass number

Multiple Choice

Which of the following correctly identifies the number of each element involved in the chemical formulas?

NH⁴ CO³

• N:4

  H:4

  C:3

  O:3

• N:1

  H:1

  C:1

  O:3

• N:0

  H:4

  C:0

  O:3

• N:1

  H:4

  C:1

  O:3

Balancing Chemical Equation/Reactions

The Law of Conservation of Mass: Matter is not created or destroyed in a chemical reaction.

Multiple Choice

A chemical reaction is represented in the equation provided. What number needs to go in front of the HC1 to balance the equation?

3H2 + 3Cl2 --> _HCl

• 2

• 3

• 5

• 6

Multiple Choice

An incomplete chemical equation is given here. Which set of numbers, placed in the blanks as the coefficients, will balance the equation shown?

_HCl + _Na2CO3 → _H2CO3 + _NaCl

• 2, 2, 1, 1

• 2, 1, 2, 1

• 2, 1, 1, 2

• 1, 2, 1, 2

Multiple Choice

An unbalanced equation is shown here. Below it is a diagram with four locations in the unbalanced equation labeled. The equation could be balanced by adding a number two (2) in which location?

• A

• B

• C

• D

Multiple Choice

According to the law of conservation of mass

• Matter is always created in a chemical reaction

• Matter is always destroyed in a chemical reaction

• Matter is created and then destroyed in a chemical reaction

• Matter is not created or destroyed in a chemical reaction

Multiple Choice

A water molecule is made up of two hydrogen (H) atoms and one oxygen (O) atom. In a chemical equation, what would be the correct way to represent 6 water molecules?

• 6H²O

• ⁶HO2

• 2H₆O₆

• ¹²H⁶O

Speed/Velocity/

Acceleration

Speed (s) equals distance divided by time. Ex.: Distance (d)= 10m and Time (t)= 5s so... s= 10m/5s= 2 m/s

Speed/Velocity/

Acceleration

Motion

Multiple Choice

Three students recorded observations about the motion of different objects. The observation of which student or students could be described as velocity

• Student one only

• Students three only

• Student one and student two

• Student two and student three

Multiple Choice

Which statement best differentiates between speed and velocity?

• Velocity is always faster than speed

• Velocity, unlike speed, includes direction

• Speed is measured in miles per hour and velocity in kilometers per hour

• Only a graph of velocity will produce a curved line

Multiple Choice

A graph of the distance traveled by a student over certain mount of time is provided. Which of the following accurately describes the students average speed?

• 3.0 m/s

• 4.0 m/s

• 5.0 m/s

• 6.0m/s

Multiple Choice

Which of these example of a description of speed?

• An airplane traveled west from New York to Los Angeles

• An apple fell from the trees and rolled 1 m north

• The average Olympic sprinter friends 8 m/s

• A train travels is 200 mph from Albuquerque to Dallas

Multiple Choice

Which of the following distinguishes the speed of an object from its velocity?

• Calculating speed Requires knowing distance calculating velocity does not require unknown distance

• Velocity includes the direction of the motion and object speed does not include the direction of motion

• Speed include the time he took the audit to travel velocity does not

• Speed include the direction of the motion of an object velocity does not include direction of motion

Multiple Choice

A dog walks a distance of 100 feet in 20 seconds of time. What is the dog's speed in feet per second?

• 5 ft./s

• 80 ft./s

• 120 ft./s

• 2000 ft./s

Force and Motion

Balanced/Unbalanced Forces

Multiple Choice

Two students apply force to a box at rest on the floor. What is the total amount of force in the newtons acting on the box in which direction

• 10 N left

• 10 N right

• 70 N left

• 70 N right

Multiple Choice

Provided is a diagram showing forces on the rocks what is the net force of the box?

• 5 N left

• 5 N right

• 75 N left

• 75 N right

Multiple Choice

The illustration provided just two boys pulling on opposite ends of a rope with different amounts of force. What is the net force on the rope?

• 10 N left

• 10 newtons right

• 90 N left

• 90 N right

Multiple Choice

A ball is rolling across the field with a force of 20 N. If the force of friction from the field is 3.7 N, what would be the net force of the ball?

• 20

• 3.7

• 17

• 16.3

Multiple Choice

The image provided shows two toy cars pushing against each other with the force given in Newtons. Which of the following describes how the two car system will behave? The two cars will...

• accelerate steadily to the right

• Move at a constant speed to the right

• Accelerate steadily to the left

• Move at a constant speed to the left

Multiple Choice

Which of the following examples best represents an object with balanced forces acting upon it?

• A boat moving through the water

• A book sitting on a high shelf

• A wagon rolling down a steep hill

• A baseball thrown in the air

Multiple Choice

A student is trying to move an object by pushing it. When the student applies 20 Newtons of force to the object, it does not move. When the student supplies 40 Newtons of force to the object it moves. Which of the following identifies the greatest amount of force the object could be applying to the student?

• 20 N

• 30 N

• 40 N

• 50 N

Multiple Choice

Which of the following situations is an example of unbalanced forces acting upon an object?

• A Rock accelerating as it rolls down a hill

• I rope being pulled from both sides with equal force

• A car moving constantly at 30 mph

• Science textbook lying on the floor

Multiple Choice

A diagram of the forces being applied to a box is provided. If the net force acting on the box 10 N toward the right, what is the magnitude of force applied by the boy pulling to the left?

• 14

• 11

• 8

• 21