Silicon dioxide powder dissolves in water. Is this a physical or a chemical change?

Which part of a feedback mechanism is able to monitor the conditions outside of cells and usually uses nerve cells to relay this information to an intergrating center

In an effort to address concerns about global warming, a power plant in portland,oregon is designed to take all of its exhaust gases from its boilers and recycle the co2 using the solvay process to make sodium hydrogen carbonate. the reaction is shown below. nh3(g) + h2o(l) + co2(g) + nacl(aq) → nahco3(aq) + nh4cl(aq) how many liters each of nh3 and co2 (both at stp) would be consumed to produce 3.00 kg of sodium bicarbonate? the volume of both nh3 and co2 would be

The chemical equation below shows the reaction of sodium (na) and chlorine (cl) to form sodium chloride (nacl). 2na + cl2 → 2nacl in this equation, which of the following is a reactant? i. sodium ii. chlorine iii. sodium chloride