Assignment
1. In a balanced chemical equation:
(a) Are atoms conserved?
(b) Are molecules conserved?
(c) Are moles conserved?
Explain your answers briefly.
2. Writing and Balancing Chemical Equations
• To balance a chemical equation:
• Identify the reaction.
• Write the unbalanced (skeleton) equation.
• Balance the equation:
• Count the number of atoms of each element on each side and determine which need to be balanced.
• Balance each element (one at a time) by placing whole numbers (coefficients) in front of the formulas containing the unbalanced clement:
• Begin with metals, then nonmetals. and then H and 0.
• Check the other elements to see if they have become unbalanced in the process of balancing the chosen element. If so. rebalance as needed.
• Do a final check to make sure all elements are balanced.
• The following information can be found in a chemical equation:
• Identity of reactants and products
• Formulas for reactants and products
• Number of formula units for reactants and products
• Number of atoms of each clement in the reaction
• Number of moles of each substance
3. Use the activity series to predict which of the following reactions will occur. Complete and balance the equations. If no reactions occurs, write "no reaction" as the product.
(a) Ca(s) + H2O(l) →
(b) Br2(l) + KI(aq) →
(c) Cu(s) + HCI(aq) →
(d) Al(s) + H2SO4(aq) →
4. Change these word equations into formula equations and balance them. Be sure to use the proper symbols to indicate the state of each substance, as given.
(a) Magnesium metal is placed into hydrobromic acid solution, forming hydrogen gas and aqueous magnesium bromide.
(b) When heated, solid calcium chlorate decomposes into calcium chloride solid, releasing oxygen gas.
(c) Lithium metal reacts with oxygen gas to form solid lithium oxide.
(d) Solutions of barium bromate and sodium phosphate combine to form solid barium phosphate and aqueous sodium bromate.
(e) Solutions of acetic acid and sodium carbonate are mixed together, forming a solution of sodium acetate, along with carbon dioxide gas and liquid water.
(f) Solutions of silver nitrate and aluminum iodide are mixed together, forming solid silver iodide and aqueous aluminum nitrate.