Bellringer 10/19 1. A substance has a pH of 2. Is it an acid or a base? 2. A substance has a pH of 8. Is it an acid or a base? 3. NaCl: is this compound Ionic, Covalent, or Both? Name it. 4. OF: is this compound Ionic, Covalent, or Both? Name it. 5. KNO 3 : is this compound Ionic, Covalent, or Both? Name it. 6. A cup of water has weighs 1 gram and has a volume of 1ml. What is its density? (D=M/V)* 7. Mr. McHugh ate 2 pounds of Taco Bell on Saturday. How many calories did he consume? (1 lb Taco Bell= 1,500 calories) …….SHOW YOUR WORK MY WAY!

Chemical Equations

Chemical Equation Def A symbolic representation of a chemical reaction - Why use the word symbolic? EX 2Na + Cl 2 2 NaCl

Bellringer 10/20 1. What shape do solids have? (Definite or indefinite?) What volume do solids have? (Definite or indefinite?) 2. What shape do liquids have? (Definite or indefinite?) What volume do liquids have? (Definite or indefinite?) 3. What shape do gases have? (Definite or indefinite?) What volume do gases have? (Definite or indefinite?) 4. Draw and label an atom of the following element: Carbon Nucleus (protons and neutrons- correct numbers!!!) Electron orbitals (electrons- correct number!!!)

2Na + Cl 2 2 NaCl Parts of a chemical Equation “equals” Or Reaction taking place Products Every thing to the right Reactants Every thing to the left Coefficient – the number of Molecules in an equation Subscript – the number of atoms in a formula

Law of conservation of mass - this is an equation - that means there needs to be equality Def – Mass can not be made or destroyed That means for an equation the number of atoms on each side need to be the same. Balancing equations – Making the number of atoms of each element equal on both sides of the arrow.

2.You can only change the Coefficients of the formulas - This will change the numbers of all the atoms of that formula. Multiply through by the subscripts Balancing equations – follow these guidelines 1.You cannot change the subscripts of the formulas -If you change the subscript, you change the chemical The problem with balancing equations – let me read from the book the section that explains balancing Did that really explain anything?

Questions to ask your self. 1.Is there a metal by itself? Yes – Balance last No – Go to #2 2.Are there any Polyatomic Ions? Yes – Treat them as if they were one element No – Go to #3 What is that? Ex – Na It is a symbol with no subscript AgNO 3 + CaCO 3 Ag 2 CO 3 + Ca(NO 3 ) 2 You can tell by If you see it on one side You will see it on the other side

3. Are there odd number of oxygens on side of the equation and an even on the other side? Yes – make the odd side even No – Go to #4 H 2 + O 2 H 2 O The number on this side? Two And on this side? One EvenOdd If you can only multiply, what is the easiest way to turn an odd number into an even number? Multiply it by two. 2

4. Start at the first element and balance through. Ex. Al + Ag 2 S  Al 2 S 3 + Ag Is there a metal by itself?Yes – Al and Ag Are there Polyatomic ions?No – How can you tell? Odd and even Oxygens?There aren’t any oxygens Start at the first element and balance through 236

HCl + Ca(OH) 2  CaCl 2 + H 2 O Is there a metal by itself?NO Are there Polyatomic ions?Yes – the OH Odd and even Oxygens?All the oxygen is in a polyatomic ions Start at the first element and balance through Where do you think the OH is on the right side of the equation? It is in the water. Rewrite like this when you have OH on one side and water on the other H X 22

Is there a metal by itself?No – go on to #2 Are there Polyatomic ions?No – How can you tell? Odd and even Oxygens?Yes Start at the first element and balance through H 2 + O 2 H 2 O 2 Make the odd oxygen in water even by Putting a two in front of it. 2 21

Some Practice 1.AgNO 3 + NaCl  AgCl + NaNO Mg + O 2  MgO 3.. H 2 O 2  H 2 O + O HCl + Ca(OH) 2  CaCl 2 + H 2 O 5.. Al + O 2  Al 2 O 3

6.. H 2 CO 3  H 2 O + CO Al + Ag 2 S  Al 2 S 3 + Ag 8.. KClO 3  KCl + O CaBr 2 + Na 2 CO 3  CaCO 3 + NaBr 10.. Mg(OH) 2 + HCl  MgCl 2 + H 2 O