Chem 103 Exam 1 review - UW Madison

What is an acid?

solution has an excess of H+ ions. a substance that can donate a proton (H⁺ ion), accept a pair of electrons, or increase the concentration of hydrogen ions in a water solution

What is a base?

solution has an excess of hydroxyl ions (OH-)

What is neutralization?

-process where acid and base are mixed until they become neutral and the PH is 7.

What are the two products of a neutralization chemical reaction?

water and salt ( The type of salt depends on acid or base added to neutralize.)

What is a weak acid?

an acid that only partially ionizes in an aqueous solution. This means that not every molecule breaks apart.

pH

is a measurement of how acidic or how basic a solution is.

Why is pH important to biology?

Cells survive in a specific pH range.

Human blood is maintain at 7pH for homostasis.

The stomach has acids to break down food.

Bile from the liver is a base which breaks down fats & grease.

What is a buffer?

a substance to help to neutralize/balance pH levels.

What are pH indicators?

They are used to tell you the pH value.

Examples are phenalphelein and bromthymol blue.

What are the properties of an acid?

taste sour, conduct electricity, corrosive, reacts with metals, turns litmus paper red.

Give examples of acids

HCL which is in your stomack.

Sulfuric acid which is used a lot in industries to make fertilzers, paints, etc.

Tums antacid used to neutralize stomach acids.

What are some uses of bases?

soaps and cleaning products

used in batteries

What are some examples of bases?

lye used to make soap.

Liquid plummer used for clogged drains. Baking Soda and Baking powder

What is the main neutral substance?

water

How is a salt chemically formed?

When you add acid or base to neutralize a solution the products formed are water and salts.

A change in pH units represents a tenfold change in the acidity of the solution (logarithmic scale). If one solution has a pH of 1 and a second solution has a pH of 2, the first solution is not twice as acidic a the second it is ______times more acidic.

ten (logarithmic)

What is a pH scale?

a logarithmic scale that indicates the pH of a solution. It ranges from 0 - 14.

On the pH scale, what numbers represent an acid?

0-6

On the pH scale, what numbers represent a base?

8-14

On the pH scale, what number represents a neutral solution?

7

What is a weak acid?

An acid that only partially ionizes (breaks down) in a solution. Weak acids are close to 7pH

What is a weak base?

A weak base will only parttally ionize in a solution. This means that not every molecule breaks apart.

What is a chemical change?

When a change in composition occurs giving new substances with new properties.

Example when wood changes to carbon. Wood and carbon do not have similar properties.

WHat is a physical change?

When a change does NOT change the composition.

What are indicators of a chemical change?

Observations such as what you see( color change, precipitant (solids in solutions)

Hear-boom Smell Taste-sour/sweet Feel-hot or cold.

Also, bubbles indicate gas..

What is the law of conservation of mass?

Mass is not created nor destroyed.

What is a chemical formula?

-chemical symbols represent molecules with subscripts to represent the number of that element.

NaCl represents table salt.

Reactants are on the right or left of the -> (yield) sign in a chemical equation.

left

Products are on the left or right of the ->(yield) sign in a chemical equation.

right

What does the -> represent in a chemical equation?

yield or to produce

What is a chemical equation?

It represents with chemical formulas a chemical change/reaction.

When one molecule splits apart and switch places this is called a __ reaction.

replacement type of chemical reaction

What is a reactant in a chemical equation?

They are substances that are present before the chemical change takes place. They are what you put into the chemical reaction to cause a chemical change.

What is a product in a chemical equation?

Chemicals that are formed during the chemical change.

When energy is absorbed in a chemical reaction it is a __reaction.

endothermic

When energy is released in a cheicial reaction it is a __reaction>

exothermic ( usually in the form of heat)

What does a neutralization chemical reaction produce?

water and salt

A chemical reaction is when a __ change has occurred.

chemical

What happens to the old molecules in a chemical reaction?

They rearrange into new molecules

What is activation energy?

The energy needed to start a chemical reaction.

What is a coefficient?

The number in front of a chemical formula which tells how many of that molecules is needed to balance the chemical equation.

Chemical reactions will produce

new substances.

A __ represents a chemical reaction

chemical equation

What happens in a chemical reaction?

bonds between atoms are broken and new bonds are formed.

Why are chemical equations balanced?

When chemical equations are balanced they have the same number of the same atom on both sides of the equation. This is because of the law of conservation of matter.

How does a catalyst increase the reaction rate?

by lowering the activation energy

Describe the types of chemcial reactions?

Synthesis A + B -> AB (single product)

Decomposition AB-> A + B ( breaks down into smaller elements)

Single Replacement AB + C -> AC + B

Double Replacement AB + CD -> AD + BC

Neutralization acid + base -> water + salt

What is a synthesis chemical equation?

When two ro more substances combine in a chemical reaction to form another substance .

What is a decomposition chemical equation?

The breakdown of a substance into two or more simpler substances.

What is a macromolecule?

They are large molecules which are needed for a living organism. They are fats, proteins, nucleic acid (DNA, RNA) and carbohydrate.

Carbon is unique and causes the formation of long chains in macromolecules because of its __

four valence electrons

What is the word chemical equation for photosynthesis?

carbon dioxide + water -> glucose and oxygen gas

What are the reactants in photosynthesis?

carbon dioxide and water

What are the products in photosynthesis?

glucose and oxygen gas

What factors influence the rate of chemical reaction?

pH concentration pressure, surface area, temperature

What is the name of the white horse on my farm?

Ghost

Atoms

-the submicroscopic particles that constitute the fundamental building blocks of mater

-each has its own unique properties (mass, physical characteristics)

Molecules

-two or more atoms joined in a specific geometric arrangement

-properties of molecules depend on the composition of those molecules

Chemistry

-the science that seeks to understand the behavior of matter by studying the behavior of atoms and molecules

The Scientific Method

-the guidelines for the practice of science

States of matter

-solid, liquid, and gas

Matter is classified by its ____________ or by the ______________

1. state

2. composition

Gas (macroscopic)

1. no fixed volume

2. compressible

Gas (microscopic)

1. gas molecules are far apart, moving fast

Liquid (macroscopic)

1. fixed volume

2. no fixed shape

3. moderately compressible

Liquid (microscopic)

1. In translational motion

2. closer together than gases

3. short range order, long range disorder

Solid (macroscopic)

1. fixed volume and shape

2. incompressible

Solid (microscopic)

1. molecules are packed closely together in fixed positions

crystalline

atoms and molecules are arranged in an ordered repeating pattern. Both short and long range order

-ex: diamond

amorphous

have short range order, but long range disorder. No repeating pattern of atoms/molecules

-ex: charcoal

Pure substances

matter with fixed composition and distinct proportions of atoms

Elements

cannot be decomposed into simpler substances (only one kind of atoms)

-elements vary in abundance

Compounds

-combinations of elements

-compounds have very different properties from the elements that make them up.

Mixtures

combination of two or more pure substances

Heterogeneous

substances are in different phases.

ex: Milk

Homogenous

all components in one phase (sometimes called a solution)

ex: koolaide

Physical properties

measured without changing the substance

ex: color, mass, density, melting or boiling point

Chemical Properties

describes how a substance reacts to form a new compound

ex: flammability

Intensive Properties

dont depend the amount of substance (think about independent)

ex: density, melting point, temp.

Extensive Properties

does depend on the amount of substance

ex: mass, volume, internal energy

Physical Change

substances change physical appearance. Without changing its identity (change in state: gas, liquid, solid)

ex: water molecules boiling

Chemical Changes

chemical reaction

ex: iron nail that rusts

Energy

is defined as the total kinetic energy plus potential energy

-the ability to do work

Work

is defined as the action of a force through a distance

equation: W=f*d

Heat

is the transfer of energy from one substance to another

Kinetic energy

the energy an object possess by virtue of its motion

equation: 1/2mv^2

Potential Energy

the energy an object possess by virtue of its position relative to other objects

ex: weight on ground (gravity acting on the weight)

Law of Conservation of Energy

Energy is neither created nor destroyed only changed from one form to another OR transferred from one object to another

Mass

is a measure of the amount of material in an object

Temperature

scientific studies use the Kelvin Scale and the Celcius scales

Kilo

1,000 (k)

Centi

.01 (c)

Milli

0.001 (m)

Micro

10^-6 (weird M sign)

Nano

10^-9 (n)

Derived Units

are formed from the seven base units

Volume

has units of length

Density

is used to characterize substances

Precision

how well measured qualities agree with one another

Accuracy

how well measured qualities agree with the "true value"