How much heat is evolved when 22.5 grams of a food sample changes the temperature of 0.42 kg of water by 4.4 degree c. assume specific heat to be 4.18 j/g/c

In an energy pyramid, which level has the most available energy?

What three things determine the shape and size of a puddle when water is poured out onto a surface

Modern pennies are composed of zinc coated with copper. a student determines the mass of a penny to be 2.482 g and then makes several scratches in the copper coaling (to expose the underlying zinc). the student puts the scratched penny in hydrochloric acid, where the following reaction occurs between the zinc and the hcl (the copper remains undissolved): zn(s) + 2 hcl(aq) → h2(g) + zncl(aq)the student collects the hydrogen produced over water at 25 °c. the collected gas occupies a volume of 0.899 l at a total pressure of 79 j mmhg. calculate the percent zinc (by mass) in the penny. (assume that all the zn in the penny dissolves.)