How does an exothermic change show that a chemical reaction occured?

During a period of discharge of a lead-acid battery, 405 g of Pb from the anode is converted into PbSO4 (s).

The half-life of Zn-71 is 2.4 minutes. if one had 100.0 grams at the beginning, how many grams would be left after 7.2 minutes has elapsed?

What is the effect of adding more CO2 to the following equilibrium reaction? CO2 + H2O H2CO3 A. More H2CO3 is produced. B. More H2O is produced. C. The equilibrium is pushed in the direction of reactants. D. no change

How could you increase the potential energy of an apple you were holding?

How many grams are present in a 5.63 liter container filled with O2 at STP?

If the heat released during condensation goes only to warming the iron block, what is the final temperature (in ∘C∘C) of the iron block? (Assume a constant enthalpy of vaporization for water of 44.0 kJ/molkJ/mol.)

Which of the following is not a disaccharide? A) sucrose B) maltose C) lactose D) amylose E) all of the above are disaccarides

The process by which a semipermeable membrane allows water molecules, small molecules, and ions to pass through while retaining large particles

Ice melting, water boiling, lighting a match, grape juice freezing. Which statement describes evidence of a chemical reaction

An ion from a given element has 22 protons and 18 electrons. what is the charge on the ion?