Formulas and equations!! Sept.28 th 2009

Reactants and Formulas Write: HCl + NaOH  NaCl + H 2 O And label the reactants and the products

We know what is a formula We have seen that a chemical formula is… A number of atoms that make up ONE compound Ex. Mg 2 O So this example will have what number of elements? Mg:2 O:1 Therefore….2 Mg and 1 Oxygen is the chemical formula for making the compound= Mg 2 O

But wait….there is more! Vocab: Coefficients- A number in front of a chemical formula(compound) used to tell the number of compounds. Ex. (The #2 in 2Pb 3 O 4 )

Subscripts Vocab: Subscripts: A SMALL number written after an element in a chemical formula telling how many of that element is in the formula. Ex. FeS 2  this two is a subscript

Write in IAN please

Alright, how many of each Mg 2 P 2 O 7 AuCl 3 C 4 H 12 O 2 2C 3 H 4 CaMgSi 3 O 8 CaHPO 3 + 3H 2 O 3CuCl 2 Pb 3 O 4

And…a little more challenging 1.Aluminum hydroxide – Al(OH) 3 2. Al=1 O=3 H=3 2. Aluminum sulfate – Al 2 (SO 4 ) 3 Al=2, S=3, O=12 3. Ammonium sulfate – 2(NH 4 ) 2 SO 4 N=4, H=16, S=2, O=8

The super deluxe shwam-bam bonus question of the day!!!! 2NH 4 [Cr(SCN) 4 (NH 3 ) 2 ] N=14, H=20, Cr=2, S=8, C=8, Cr=2 Ammoniumtetrathiocyanatodiaminechromate (III)

From Formula’s to Equations HCl + NaOH  NaCl + H 2 O Now HCl is an acid and NaOH is a base So…. 1. What is the product of this reaction? 2. When the acid and base mix what is the product’s pH?

Lets look at this chemical EQUATION again!!!!! HCl + NaOH  NaCl + H 2 O What happened here? Which atom ‘got lost’ or disappeared? That’s right…none. All reactions follow the law of conservation of mass! In fact, if you weigh all the products in a reaction, it must weigh the same as the reactants.

Vocab: The law of Conservation of Mass- the mass of substances in a closed system will remain constant, no matter what processes are acting inside the system.

Handout: Counting Atoms Counting Atoms In the formulas there are numbers written smaller and lower than the letter symbols. They are called subscripts and indicate how many atoms of that element are present. If a number is written in front of a formula it is called a coefficient. It represents how many molecules of that compound are present. To determine the individual number of atoms use the distributive property of multiplication. Write the symbols of each element and calculate how many atoms of each element are present in the following compounds. Also give a total number for the atoms that are in the formula.

Independent practice Ex. NaHCO3 Na- 1 atom H- 1 atom C- 1 atom O- 3 atoms Total= 6 atoms Ex. 4 CO2 C- (4 X 1)= 4 atoms O- (4 X 2)= 8 atoms Total= 12 Atoms 1. C2H4O2 2. Mg(OH)2 3. H3PO4 4. 2H2SO4 5. (NH4)3PO4 6. C6H12O6 7. 4CaCO3 8. 5HNO3