Advertising claims sometimes state that adding something mechanical to a car's engine will allow it to recover 100 percent of the energy that comes from burning gasoline. You should be skeptical of such claims because they violate the

When the chemicals iron sulfide (fes) and hydrochloric acid (hcl) are combined, bubbles appear from the mixture. 1. does the appearance of bubbles indicate a physical or chemical change? 2. why do the bubbles indicate this change? 3. what property is this?