Asolution contains some or all of the ions cu2+, al3+, k+, ca2+, ba2+, pb2+, and nh4+. the following tests were performed, in order, on the solution. addition of 6 m hcl produced no reaction. addition of h2s with 0.2 m hcl produced a black solid. addition of (nh4)2s produced a white solid. addition of (nh4)2hpo4 in nh3 produced no reaction. the final supernatant when heated produced a purple flame. identify which of these ions were present in the solution, which were absent, and for which ones no conclusions can be drawn.

the volume of fluid displaced would equal the volume of the gas. use a gas syringe - this is a laboratory instrument that can be used to withdraw a certain volume of gas from a closed system or to measure the volume of gas from a chemical reaction.

nacl or sodium chloride is an ionic compound. this is because an ionic compound pertains to a compound that consists of positively and negatively charged ions. in this case, na (sodium) has a tendency to lose one electron when it reacts with with other atoms, so the resulting sodium ion contains 11 protons and 10 electrons, thus making it positively charged (na+), when chlorine reacts, it usually gains one electron to form an ion called chloride, thus making it negatively charged ( since the ions are oppositely charged, they attract.

answer: semi-infinite solid initially at a uniform temperature of 400 ◦c is cooled at its surface by convection. the cooling fluid at a constant temperature of 200 ◦c has a convective coefficient (ha) of 250 w/m2.k. the physical properties of the solid: k = 20 w/m.k and α = 4 * 10-5  m2/s. using δx = 0.04 m and δt = 10 s. write the finite difference equations describing the transient heat transfer of the first five δx and the temperature profile after 30 s.