Ch 6 Review Chemical Reactions

What three things can indicate a chemical change occurred? 1. 2. 3.

A + B  AB Where in molecules is chemical energy stored? What happens to atoms during a chemical reaction? A + B  AB

What is the general name of the substance(s) that change(s) during a reaction? Which is the general name of the substance(s) that results from a reaction? AB + C  AC + B

Endothermic OR Exothermic? releases energy into the surroundings ? absorbs energy from surroundings ? stores energy in bonds ? usually results in light or heat ? changes light energy into plants ?

S, D, SR, DR, or C? Methane burns with oxygen – Has 2 compounds on either side – Photosynthesis – 1 element is oxidized, 1 element is reduced – Digestion – Breaks into at least two products -

S, D, SR, DR, or C? Makes a larger, more complex compound – Results in carbon dioxide and water - Electrolysis to make H2 and O2 gases - Making sodium chloride (NaCl) - Has a single element on either side –

Which numbers can you change to balance? Subscripts or Coefficients Why do reactions need to be balanced? If the reaction is balanced, the mass of the reactions equals the mass of the _____________.

What is the Law of Conservation of Matter? Explain the Law of Definite Proportions. How do you know when a reaction is in equilibrium?

Balance the following reactions and identify the type of reaction. ____ K3PO4 + ____ HCl  ____ KCl + ____ H3PO4 ____ KClO3  ____ KCl + ____ O2 ____ Na +____ I2  ____ NaI ____ C3H8 + ____ O2  ____ CO2 + ____ H2O ____ Zn + ____ HCl ---> ____ ZnCl2 + ____ H2

Went from neutral (0) to (+2) Went from (+2) to Neutral (0) If a substance accepts electrons, is it oxidized or reduced? Zn was oxidized Went from neutral (0) to (+2)  Zn Cl Cu + Cl Zn Cu + Cu was reduced Went from (+2) to Neutral (0)

Name 4 factors that can speed up chemical reactions. 1. 2. 3. 4.

What would happen to foods if we didn’t have refrigeration and how does this relate to chemical reactions?