Science Final Study Guide

what are reactants?

the starting materials that undergo the change

what are the products?

the materials that are a result of the change

what is the law of conservation of mass

matter cannot be created or destroyed

How do we demonstrate the law of conservation of mass in balancing chemical equations? 

When we balance equations the same materials/elements are on both sides of the equation, we never lose any. 

what are the patterns for each type of chemical equation?

• Synthesis: A + B = AB

• Decomposition: AB = A + B

• Single Replacement: A + BC = AB + C

• Double Replacement: AB + CD = AC + DB

• Combustion: C_x+H_y+O₂ → CO₂+H₂O

What are the 5 ways to speed up reaction rates?

•  Increase surface area

• Decrease volume

• Add more particles

• Add a catalyst

• Increase temperature

Knowing these 5 ways to speed them up, what are 5 ways to slow reaction rates down?

•  Decrease surface area

• Increase volume

• Take away particles

• Don’t add a catalyst

• Decrease temperature

What are characteristics of acids? 

Sour, conducts electricity, corrosive, can react strongly with metals

What are examples of acids?

Citrus fruit, Vitamin C

What are characteristics of bases?

Bitter, slippery, conducts electricity, corrosive, won’t react with metals

what are examples of bases

Shampoo, cleaning products 

The pH scale runs from 0-14. Where is the following located on the scale?

• Acids

0-6

The pH scale runs from 0-14. Where is the following located on the scale?

• Bases

8-14

The pH scale runs from 0-14. Where is the following located on the scale?

• Neutral

7

Describe the following indicators and how well they each determine whether a substance is an acid or a base and pH value:

• Red and Blue litmus paper

The blue paper turned red when it was an acid and the red paper turned blue when it was a base. It’s accurate in determining an acid or a base, but it’s not precise and won’t give you an exact number. 

Describe the following indicators and how well they each determine whether a substance is an acid or a base and pH value:

• Red/Purple cabbage juice

You add the juice to a liquid/substance and it changes colors corresponding to the PH scale. This was fairly accurate, but it required a lot of the indicator and it was difficult to determine the colors because of how light a shade they were. 

Describe the following indicators and how well they each determine whether a substance is an acid or a base and pH value:

• pH paper

This one was very accurate and the colors changed to a color that corresponded to a number on the bottle. This one was specific and gave you an exact number. 

What are characteristics of an exothermic reaction?

It releases energy and becomes warmer. 

What are 2 examples of an exothermic reaction?

•  A handwarmer: when shaken the iron reacts with oxygen and and releases heat

• A campfire: wood reacts with oxygen and it produces heat and light

What are the characteristics of an endothermic reaction?

It absorbs energy and it becomes cooler.  

What are 2 examples of an endothermic reaction?

•  An instant cold pack: when the chemicals inside are combined, they draw in more energy than they let off and become cool 

• A baking soda and vinegar reaction: when the two combine, they absorb heat from the surroundings and the temperature drops. 

What is a Limiting Reactant?

 A part in the equation that limits the reaction from continuing to go. 

What is an Excess Reactant?

A part of the equation that has leftovers because the limiting reactant stopped the reaction from continuing. 

What is a short description of Gravitational Force?

An attractive force that acts between any two objects

What is a short description of Electromagnetic Force?

A force associated with charged particles, which has two aspects, electrical force and magnetic force

Where do we see the electromagnetic force affecting the atom?

It keeps the electrons around the nucleus 

What is a short description of Strong Force?

The attractive force that binds protons and neutrons together in the nucleus

Where do we see the strong force affecting the atom?

The strong force is fighting the electromagnetic force to keep the protons together in the nucleus.

What is a short description of Weak Force?

The powerful attractive force that occurs during nuclear decay and acts over a short range

What is Radioactive Decay?:

An unstable nucleus loses energy by emitting radiation by particles or waves

What is Radioactivity?

The process in which unstable nucleus emits charged particles and energy

What is the definition of Radioisotope

An isotope with an unstable nucleus

What happens in Alpha Decay?

An unstable nucleus emits two protons and two neutrons to stabilize

What is an Alpha Particle?

A positively charged particle that’s emmited by radioactive nuclei made up of two protons and two neutrons

What happens in Beta Decay?

An electron is emitted from an unstable nucleus

What is a Beta Particle?

An electron emitted by an unstable nucleus 

What happens in Gamma Decay?

 A penetrating ray of energy is emitted by an unstable nucleus

What is a Gamma Ray/Radiation?

High energy, invisible, electromagnetic radiation, has no mass and no charge

What is Half Life?

The time required for half of a radioactive  isotope sample to decay

How are nuclear decay and Half-Life used by NASA?

• It can be used as a long term power source for space exploration

• The longer the half-life the better for power usage

How are nuclear decay and Half-Life used by scientists and archeologists?

• you can determine the age of different objects using radioactive/carbon dating. 

• Depending on how stable/unstable something is you can determine whether or not it’s been there for a long time. 

What is Nuclear Fission?

Splitting of an atomic nucleus into 2 smaller parts

What happens in a Chain Reaction in nuclear science?

Neutrons released during the splitting of an initial nucleus trigger a  series of fission.

Where do we see chain reactions taking place?

• Nuclear power plants to generate electricity

• Creation of nuclear weaponry

What are benefits of using nuclear power?

• No greenhouse gasses are emitted

• Constant and secure source of power

What are negatives of using nuclear power?

• High upfront costs

• The question of managing the radioactive waste

What is Nuclear Fusion?:

A process in which the nuclei of 2 atoms combine to form a larger nucleus

How is nuclear fusion used?

Currently it’s in the testing and developing phase

What is the ITER project, and what is its hope for the future?

The world’s most complex fusion experiment, and they want to make it a viable large scale of commercial energy

what is motion

the continuous change in the position of an object over time, relative to a fixed point or frame of reference.

What is the difference between distance and displacement?

Distance is the total length of the path that the object took, and displacement only looks at the starting point from the ending point

• Position vs. Time

  • What is on the y-axis?

position

• Position vs. Time

  • What is on the x-axis?

time

•    Velocity vs. Time 

  • What is on the y-axis?

Velocity 

•    Velocity vs. Time 

  • What is on the x-axis?

time

What is Inertia?

The natural tendency of an object to resist change in their current state of motion. 

What is an example of Law One?

When you slam on the brakes your body lurches furrowed.

Describe Law Two:

• What do the variables stand for in F = m x a?:

force=mass x acceleration

What is an example of Law Two?

You push an empty grocery cart into the store and it’s easier than when you push a full cart back out

What is an example of Law Three?:

When you walk your foot is pushing against the ground and the ground is pushing back with an equal and opposite force

what is friction

The force that resists an object from moving over another object

what is air resistance

The frictional force that the air pushes against objects moving through the air

How can Air Resistance be used to protect an egg when dropped from a height?

By adding something like a parachute you decrease the kinetic energy and therefore increase the air resistance

what is momentum

The force gained by a moving object

What do the variables stand for in p = m x v?:

Momentum = mass x velocity

How is momentum transferred in Elastic Collisions (Bounce off each other)?

Temporary elastic deformation 

What is an example of an Elastic Collision?

a golf ball squishes when it hits a club

How is momentum transferred in Inelastic Collisions (Stick together)

The momentum of the faster object transfers to the slower object

What is an example of an Inelastic Collision?

A ball of clay is dropped onto the floor and splats and does not bounce back

What is Impulse?

The overall effect of a force applied to an object over a period of time

What do the variables stand for in Δp = F x t

Change in momentum = net force x time

What is the difference between F x t  and F x t?

First one is large force in short time (egg hitting wall/concrete) and second is small force in long time (a cushion or foam on the ground to slow down impact time) 

What are examples of materials that work well to protect an egg from breaking when dropped from a height? How do they absorb all the force of impact or extend the time of impact?

A thick and fluffy foam works well because it slows down the impact time to the ground and creates a barrier between the hard ground. A parachute of sorts using something like a plastic garbage bag also works well because it extends the time of impact and it decreases the kinetic energy.  

What is Work (as defined in physics)?

The product of distance and the force in the direction an object moves

What do the variables stand for in W= F x d?

Work = force x distance

What is the unit for Work?

Joules 

What is Power (as defined in physics)?

the rate of doing work

What do the variables stand for in P = W / t?

Power = work / time 

What is the unit for Power?

watts

What are the 6 Simple Machines?

• Lever

• Pulley

• Wedge

• Wheel and axle

• Inclined plane

• screw

What is an example of each simple machine in the real world?

• Lever: a seesaw

• Pulley: a flag pole 

• Wedge: an axe

• Wheel and axle: a doorknob

• Inclined plane: a ramp

• Screw: a jar

What is Energy?

The ability to do work

What is the unit for energy?

joules

What is Potential Energy?:

Energy that is stored as a result of position or shape

what is kinetic energy

The energy an object has due to its motion

What does the Law of Conservation of Energy state?

Energy cannot be created or destroyed

what is a longitudinal wave

A wave in which the vibration of the medium is parallel to the direction the wave travels

what are the parts of a longitudinal wave

Rarefaction (the more spread out bits), compression (the tightly compacted bits), and wavelength (the section between compression to compression)

What is an example of energy that travels in a longitudinal wave?

sound energy

what is a transverse wave

A wave that causes a medium to vibrate at right angles to the direction of the wave

what are the parts of a transverse wave

The crest (the highest point on the hills), amplitude (the height from the horizontal line to the top of the hill),  wavelength (the distance between the tops of one hill to the next), the equilibrium position (the line that goes horizontal through the wave), and the trough (the point at the bottom of the valley). 

What is an example of energy that travels in a transverse wave?

Light and electromagnetic radiation (microwaves, radio waves, X-rays)

Visible Light is found on what spectrum?

The portion of the electromagnetic spectrum that human eyes can see

What are the Primary Colors of Light?

red, green, and blue

What are the Secondary Colors of Light?

cyan, magenta, and yellow

What happens when you mix all the colors of light together?: 

white light

Do colors of light become more or less vibrant when you mix them?

more vibrant

How do you create darker or duller colors of light?

Decrease intensity or cancel out frequencies

What is Electrical Energy/Electricity?

The presence and flow of electrical charge

what is a series circuit

Components in one loop