Chemistry Chapter 8 Class Notes 3e243q

Objective: Students will be able to write several unbalanced equations when they read descriptions of reactions. Students will also read equations and translate them into words. Pre class: 4. Copy this equation into your notes Determine what each symbol means. NaCN(s) + HCl(aq)  NaCl(aq) + HCN (g)

4. Copy this equation into your notes Determine what each symbol means.

NaCN(s) + HCl(aq) 

NaCl(aq) + HCN (g)

See page 265 and the periodic table and the table of common ions (CNis cyanide ion) Make a table showing this in your notebook. Symbol Meaning NaCN (s) + HCl Hydrochloric acid (aq)  NaCl (aq) + HCN (g)

An example of an unbalanced equation for a reaction which is endothermic:

Heat + Ba(OH)2*8H20 (s) + NH4SCN(s)  Ba(SCN)2(l) + NH3 (g) + H20(l) Observations of the demonstration. Reactants Products Temperature (energy) changes

Heat + Ba(OH)2*8H20 (s) + NH4SCN(s)  Ba(SCN)2(l) + NH3 (g) + H20(l)

Heat + Ba(OH)2*8H20 (s) + NH4SCN(s)  Ba(SCN)2(l) + NH3 (g) + H20(l)

Inventory of atoms reactant side Ba O H N SCN

Product side

Heat + Ba(OH)2*8H20 (s) + 2NH4SCN(s)  Ba(SCN)2(l) + 2NH3 (g) +10 H20(l)

Review diatomic elements see page 23- define and list all examples: O2, H2, F2, Cl2, I2, Br2, N2 Why will you need to recognize these when writing an equation for a reaction like this? Iron combines with oxygen to form Iron(II)Oxide Work on questions Page 266 # 9,10,17 a&b write equations from sentences which describe equations. Translate formula equations into words equations.

Work on questions Page 266 # 9,10,17 write equations from sentences which describe equations. Translate formula equations into word equations. hints: solid silicon is just Si, solid magnesium is just Mg