Balancing the following equations:
(a)pcl5(s) + h2o(l) -> pocl3(l) + hcl(aq)
(b)cu + hno3 -> cu(no3)2 + h2o + no
(c)h2 + i2 -> hi
(d)fe + o2 -> fe2o3
(e)na + h2o -> naoh + h2
(f)(nh4)2cr2o7 -> cr2o3 + n2 + h2o
(g)p4 + cl2 -> pcl3
(h)ptcl4 -> pt + cl2

a) PCl5(s)  +  H2O(l)  ↔  POCl3(l)  + 2HCl(aq)  

b) 3Cu  +  8HNO3  ↔  3Cu(NO3)2  +  4H2O  +  2NO

c) H2  +  I2  ↔  2HI

d) 4Fe  +  3O2  ↔  2Fe2O3

e) 2Na  +  2H2O  ↔ 2NaOH  +  H2

f) (NH4)2Cr2O7  ↔  Cr2O3  +  N2  + 4H2O

g) P4  +  6Cl2  ↔  4PCl3

h) PtCl4  ↔  Pt  + 2Cl2

Explanation:

a) PCl5(s) +  H2O(l)  ↔  POCl3(l)  +  2HCl(aq)

                     1 - P - 1

                   5  - Cl - 5

                     1 - O - 1

                      2 - H -2

b) 3Cu(0)  +  8HN(+5)O3  ↔  3Cu(+2)(NO3)2  +  4H2O  + 2N(+2)O

∴ Cu (0) → Cu (+2)   in parenthesis the oxidation state

⇒ Cu : lose 2e-

∴ N (+5) → N (+2)

⇒ N : gains 3e-

                        3 - Cu - 3

                        8 - N - 8

                       24 - O - 24

                        8 - H - 8

c) H2  +  I2 ↔ 2HI

            2 - I - 2

            2 - H - 2

d)  4Fe  +  3O2  ↔  2Fe2O3

              4 - Fe - 4

              6 - O - 6

e)  2Na  +  2H2O  ↔  2NaOH + H2

                  2 - Na - 2

                  2 - O - 2

                  4 - H - 4

f) (NH4)2Cr2O7  ↔  Cr2O3  +  N2  + 4H2O

                     2 - N - 2

                      2 - Cr - 2

                       7 - O - 7

                      8 - H - 8

g) P4  +  6Cl2  ↔  4PCl3

                  4 - P - 4

                  12 - Cl - 12

h) PtCl4 ↔  Pt + 2Cl2

              1 - Pt -1

             4 - CL - 4

in chemistry, a solution’s concentration is how much of a dissolvable substance, known as a solute, is mixed with another substance, called the solvent. the standard formula is c = m/v, where c is the concentration, m is the mass of the solute dissolved, and v is the total volume

it should have an internal chamber and two thermometers sticking out of the top. the internal chamber will also be closed off from the outside.