Chapter 6 test

No

Are catalysts permanently changed in a reaction?

All of the atoms present at the start of the reaction are present at the end of the reaction, they are equal to each other.

At the end of a chemical reaction, what is the total mass of the reactants compared to the total mass of the products?

A physical change is a change of the appearance of a substance but it does not change the chemical makeup. A chemical change changes the original substance and makes it into a new substance. Those are the differences between a physical and chemical change.

Compare a physical change and a chemical change.

AN open system is like a wood fire because products of the wood fire have escaped up the chimney or into the room (except for the ash)

Describe an open system.

A synthesis reaction is 2 or more elements combines together to make a new substance. A decomposition reaction breaks down substances to make it simpler.

Describe the difference between a synthesis reaction and a decomposition reaction.

Situation A is an exothermic reaction because the gas being released into the air by the chemical reaction between the fire and the wood. Situation B would be endothermic because it is absorbing heat from its surroundings causing the new solution to become cooler.

For each situation described below, tell whether the reaction is endothermic or exothermic. Explain your reasoning in terms of the energy of the reactants and products. A) A log burns in a fireplace, giving off gasses and leaving behind ash. B) When vinegar and baking soda are mixed, new substances form and the solution becomes cooler.

By preventing reactants from coming together

How do most inhibitors work?

Activation energy can be a spark

In a reaction that makes water from hydrogen gas and oxygen gas, where does the activation energy come from?

Synthesis, decomposition, and replacement

In what three categories can chemical reactions be classified?

When you increase the temperature, it will increase the chemical reaction rate.

In what way is temperature related to chemical reaction rates?

According to conservation of mass, all atoms are present at the end so balancing equations help keep the equal number of atoms

Relate the writing and balancing of a chemical equation to the principle of conservation of mass.

It is because you need more reactant particles together more often and with more energy

To increase the rate of a reaction, why would you increase the concentration of the reactants?

Synthesis

Two or more substances combine to make a more complex compound

Surface area, temperature, concentration, and the presence of catalysts or inhibitors.

What are five factors that affect the rate of a chemical reaction?

product

What are the substances that you have when a chemical reaction is complete called?

reactants

What are the substances you have at the beginning of a chemical reaction called?

yield

What do you read the arrow in a chemical equation as meaning?

It tells you the relative amount of a reactant or a product that takes part in a reaction.

What does a coefficient tell you?

It is a short and easy way to show a chemical reaction using symbols instead of words.

What is a chemical equation?

An example is a pear in a glass dome. The total mass of the pear and the substances produced during its decay are contained by the glass dome.

What is an example of a closed system?

activiation energy

What is the minimum amount of energy needed to start a chemical reaction?

It states that during a chemical reaction, matter is neither created nor destroyed.

What is the principle called the conservation of matter?

It would be a physical change because the water is still water even in the form of two gases.

When an electric current is passed through water during the process of electrolysis, two gases are formed. One gas has the boiling point of - 183 C and the other has a boiling point of -253 C. Was this event a physical change or a chemical change. Explain.

Chemists say an equation is balanced when it accurately represents conservation of matter.

When is a chemical equation balanced?

Increasing the surface area allows more particles to react than with less surface area

Why does surface area of a reactant influence the rate of the reaction?

Many chemical reactions happen at temperatures that would kill living things. The biological catalysts are specific for different chemical reactions.

Why must living things rely on thousands of catalysts for chemical reactions necessary for life?

Decomposition

compounds break down into simpler products

Replacement

one element replaces another in a compound, or two elements in different compounds trade places