Chemical Reactions Essential Unit 5

How did we describe chemical change? A change in color Production of a gas Formation of a precipitate How did we describe chemical change?

A representation of a chemical reaction in which the reactants and products are expressed as formulas. Reactants  Products Examples: NaOH  Na+ + OH- Mg(s) + 2HCl  Mg+ + H2(gas) + 2Cl- Pb(NO3)2 + 2NaI  PbI(s) + Na2(NO3)2 Chemical Equations

Mass is neither created or destroyed in a chemical reaction. Conservation of Mass

Chemical Equations Whether you burn one carbon atom or six carbon atoms, the equation used to describe the reaction is always the same.

Chemical Equations Whether you burn one carbon atom or six carbon atoms, the equation used to describe the reaction is always the same.

Chemical Equations Whether you burn one carbon atom or six carbon atoms, the equation used to describe the reaction is always the same.

Conservation of Mass Balancing Equations H2 + O2  H2O

Conservation of Mass Balancing Equations Se+ + O2  SeO2

Conservation of Mass Balancing Equations HgO  Hg+ + O2

Conservation of Mass Balancing Equations Fe2O2 + H2  Fe2+ + H2O

Conservation of Mass Balancing Equations C6H12O6 + O2  CO2 + H2O

Avogadro’s Number 6.02 x 1023 Moles (mol)

Molar Mass Simply put, the mass of 1 mole of a substance For an element, the molar mass is the same as its atomic mass (or atomic weight) expressed in grams. The molar mass of carbon is 12.0 grams. The molar mass of sulfur is 32.1 grams. Molar Mass

You calculate the molar mass of a compound by adding up the atomic masses of its component atoms and then expressing this sum in grams. A carbon dioxide molecule is composed of one carbon atom (12.0 amu) and two oxygen atoms (2 × 16.0 amu = 32.0 amu). Carbon dioxide has a molar mass of 44.0 grams. Counting with Moles

Suppose you have 55. 0 grams of CO2 Suppose you have 55.0 grams of CO2. To calculate how many moles of CO2 you have, multiply the mass by a conversion factor. You can check your answer. Mole-Mass Conversion

Mole-Mass Conversion How many grams are in 1 mole of NaOH? How many moles are in 58.45 grams of NaCl? How many grams are in 0.1 FeCl2? How many moles are in 4.03 grams of MgO? Mole-Mass Conversion

N2 + 3H2  2NH3 How many moles of NH3 can be made if 7.5 moles of H2 react with enough nitrogen. What mass of NH3 can be made from 35.0g of nitrogen? Mole Ratios