CH 305 Chapter 6 part 2: Neutralizing the Threat of Acid Rain pH - Concentration Calculations Links pH, [H+] or [OH-] with [acid] or [base] with mass. Method: 1. Write equation for acid or base dissociating in water: Acid →one ormore H+and anion Base →one ormore OH-and cation. (NH3forms NH4OH by taking a H+from water) 2. Determine desired [H+] for the acid, or [OH-] for the base 3. Use 1. and solution volume to find moles of the acid or base 4. Determine the mass of this acid or base Example 1. How many g of NaOH is needed to prepare 500ml of a solution with pH= 10.4? Example 2: SO3is an acid anhydride and forms sulfuric acid. Write the balanced equation for this process. If we have burnt enough coal to create 2kg of SO3, and ALL of this ends up in 3000L of distilled water, what would be the pH of this pool of sulfuric acid? Acid-Base Reactions (Includes TITRATIONS) Links molarity, balancing equations, stoichiometry, acid-base reactions and pH. Method: 1. Write the balancedreaction. (NOTE: some bases and acids have more than one H+or OH-) 2. Find amount of the given reactant in moles. (if the pH is given instead this needs another step) 3. Determine how much of the other reactant is needed or how much of a product is formed. Example 1: A 25ml sample of sodium hydroxide is neutralized by 35 ml of sulfuric acid (0.2M). How many moles of NaOH were present in the sample? What was the concentration of the sodium hydroxide solution? What would be the pH of each solution before use? Example 2: How much hydrochloric acid would be needed to dissolve a stick of chalk? Assume the chalk is 100% calcium carbonate and weighs 2g. The pH of the acid you are provided is 2.3.
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