Unit 4: ToxinsUnit 4: Toxins

Intro Chemistry

Chemical ToxinsChemical Toxins

Chemistry is the study of matter and the Chemistry is the study of matter and the changes that it undergoes.changes that it undergoes.

We have learned about how chemical We have learned about how chemical compounds are formedcompounds are formed

We have also learned the language of We have also learned the language of chemistry, chemical formulaschemistry, chemical formulas

Certain chemicals interact with the human Certain chemicals interact with the human body in a negative way and are known as body in a negative way and are known as toxinstoxins

Now we will equations for chemical Now we will equations for chemical reactions to learn about toxic substances.reactions to learn about toxic substances.

Keeping Track of AtomsKeeping Track of Atoms

Law of Conservation of MatterLaw of Conservation of Matter Conservation of MatterConservation of Matter:: in all chemical and in all chemical and

physical changes, matter is neither created physical changes, matter is neither created or destroyedor destroyed• The total mass in a chemical reaction remains The total mass in a chemical reaction remains

constantconstant

Antoine Lavoisier:Antoine Lavoisier:• Made accurate and precise Made accurate and precise

measurements during chemical reactionsmeasurements during chemical reactions• Found that the total mass at the Found that the total mass at the

beginning = total mass at end of reactionbeginning = total mass at end of reaction

Chemical ReactionsChemical Reactions A chemical change is really a chemical reactionA chemical change is really a chemical reaction Has two parts: Has two parts:

• Reactants:Reactants: the substances you start with the substances you start with

• Products:Products: the substances you end up with the substances you end up with

The reactants turn into the productsThe reactants turn into the products

4 Fe + 3 O4 Fe + 3 O22 2 Fe 2 Fe22OO33

Reactants Reactants products products

Ways to Express a Chemical Ways to Express a Chemical ReactionReaction

The way atoms are joined is changed in a The way atoms are joined is changed in a chemical reaction.chemical reaction.Can be described several ways:Can be described several ways:

1. In a 1. In a sentence sentence Copper reacts with chlorine to form copper (II) Copper reacts with chlorine to form copper (II)

chloride.chloride.

2. In a 2. In a word equationword equationCopper + chlorine Copper + chlorine copper (II) chloride copper (II) chloride

3. In 3. In chemical formulaschemical formulas::Cu + ClCu + Cl22 CuCl CuCl22

Symbols in equations-Symbols in equations- the the arrow arrow separates the separates the

reactants from the productsreactants from the products (s) or (s) or after the formula = solid after the formula = solid (g) or (g) or after the formula = gas after the formula = gas (l)(l) after the formula = liquid after the formula = liquid (aq)(aq) after the formula - dissolved after the formula - dissolved

in water, an aqueous solution in water, an aqueous solution

Symbols used in equationsSymbols used in equations

indicates a indicates a reversible reversible reactionreaction

shows shows that that heat heat is supplied to the is supplied to the reactionreaction

is used to indicate a is used to indicate a catalystcatalyst is supplied, in this case, is supplied, in this case, platinum.platinum.

heat ,

Pt

What is a catalyst?What is a catalyst?

A A catalystcatalyst is a substance that is a substance that speeds up a reaction, without speeds up a reaction, without being changed or used up by the being changed or used up by the reaction.reaction.

Enzymes are biological or protein Enzymes are biological or protein catalysts.catalysts.

Skeleton and Balanced Skeleton and Balanced EquationsEquations

Use formulas and symbols to describe a Use formulas and symbols to describe a reactionreaction

Don’t indicate how many of each Don’t indicate how many of each element/compound element/compound

Balanced equations:Balanced equations: the number of atoms the number of atoms of each element is the same on both sides of each element is the same on both sides of the reaction.of the reaction.

Use coefficients to balance equationUse coefficients to balance equation

Coefficients and SubscriptsCoefficients and Subscripts

Coefficients:Coefficients: large whole numbers placed large whole numbers placed in front of formula which represents in front of formula which represents number of units of that compoundnumber of units of that compound

Subscript:Subscript: small whole number placed in small whole number placed in chemical formula to represent number of chemical formula to represent number of atoms of an element in a compoundatoms of an element in a compound

4 Fe + 3 O4 Fe + 3 O22 2 Fe 2 Fe22OO33

Coefficient subscript

Study Buddy ReviewStudy Buddy Review

What is the Law of Conservation of What is the Law of Conservation of mass?mass?

What does the symbol (l) mean?What does the symbol (l) mean? What does (aq) mean?What does (aq) mean? What is a coefficient?What is a coefficient? What is a subscript?What is a subscript?

How to Balance How to Balance Chemical EquationsChemical Equations

Balanced EquationBalanced Equation

A balanced equation has the A balanced equation has the same number of atoms of each same number of atoms of each element on both sides of the element on both sides of the equationequation

Atoms can’t be created or Atoms can’t be created or destroyeddestroyed

All the atoms at the beginning All the atoms at the beginning must appear in the endmust appear in the end

C + OC + O22 CO CO We need one more oxygen in the We need one more oxygen in the

products.products. Can’t change the formula, because it Can’t change the formula, because it

describes what it is (carbon monoxide in describes what it is (carbon monoxide in this example)this example)

C + O COO

Must be used to make another COMust be used to make another CO But where did the other C come from?But where did the other C come from?

C +O

C

OO

OC

Must have started with two CMust have started with two C 2 C + O2 C + O22 2 CO 2 CO

C

+O

C

OO

OC

C

Rules for balancing:Rules for balancing:

Assemble, write the Assemble, write the correct formulascorrect formulas for for all the reactants and productsall the reactants and products

Count the number of atoms of each type Count the number of atoms of each type of element appearing on both sidesof element appearing on both sides

Balance the atoms of an element one at a Balance the atoms of an element one at a time by adding coefficients (the numbers time by adding coefficients (the numbers in front) - save H and O until LAST!in front) - save H and O until LAST!

Check to make sure it is balanced.Check to make sure it is balanced.

Never change a subscript to balance an Never change a subscript to balance an equation.equation.• If you change the formula you are If you change the formula you are

describing a different reaction.describing a different reaction.

• HH22O is a different compound than HO is a different compound than H22OO22

Never put a coefficient in the middle of Never put a coefficient in the middle of a formulaa formula• 2 NaCl is okay, Na2Cl is not.2 NaCl is okay, Na2Cl is not.

Balancing Equations ExamplesBalancing Equations Examples

HH22 (g) (g) + O+ O22 (g) (g) H H22O (l)O (l)

Zn + HCl Zn + HCl H H22 + ZnCl + ZnCl22

Pb (NOPb (NO33))22 + K + K22S S PbS + KNO PbS + KNO33