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Formulas and equations!!

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

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Formulas and equations!!

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  1. Formulas and equations!! Sept.28th 2009

  2. Reactants and Formulas • Write: HCl + NaOH NaCl + H2O And label the reactants and the products

  3. We know what is a formula • We have seen that a chemical formula is… • A number of atoms that make up ONE compound • Ex. Mg2O • 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= Mg2O

  4. 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 2Pb3O4)

  5. 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. FeS2  this two is a subscript

  6. Write in IAN please

  7. Alright, how many of each • Mg2P2O7 • AuCl3 • C4H12O2 • 2C3H4 • CaMgSi3O8 • CaHPO3 + 3H2O • 3CuCl2 • Pb3O4

  8. And…a little more challenging • Aluminum hydroxide – Al(OH)3 • Al=1 O=3 H=3 2. Aluminum sulfate – Al2(SO4)3 Al=2, S=3, O=12 3. Ammonium sulfate – 2(NH4)2SO4 N=4, H=16, S=2, O=8

  9. The super deluxe shwam-bam bonus question of the day!!!! • 2NH4[Cr(SCN)4(NH3)2] • N=14, H=20, Cr=2, S=8, C=8, Cr=2 • Ammoniumtetrathiocyanatodiaminechromate(III)

  10. From Formula’s to Equations • HCl + NaOH NaCl + H2O • 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?

  11. Lets look at this chemical EQUATION again!!!!! • HCl + NaOH NaCl + H2O • 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.

  12. 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.

  13. 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.

  14. 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

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