Question #2343f

Jan 15, 2015

I'll start you off on a couple of these.

Chromium plus fluorine - this reaction depends on the conditions at which it takes place. For example, at very high pressure and temperature (around 200 atm and 400 degrees Celsius), you'll get chromium (VI) fluoride, ${\text{CrF}}_{6}$

$C {r}_{\left(s\right)} + 3 {F}_{2 \left(g\right)} \to C r {F}_{6 \left(s\right)}$

For lower temperature and pressure values, two other reactions can take place

$C {r}_{\left(s\right)} + 5 {F}_{2 \left(g\right)} \to 2 C r {F}_{5 \left(s\right)}$ - here chromium (V) fluoride is formed, and

$2 C {r}_{\left(s\right)} + 3 {F}_{2 \left(g\right)} \to 2 C r {F}_{3 \left(s\right)}$, in this case chromium (III) fluoride being formed.

All these reactions are called synthesis reactions - reaction in which two or more simple compounds combine to form a more complex one.

Barium chlorate (heated)

When heated, barium chlorate will decompose to barium chloride and oxygen according to this reaction:

$B a {\left(C l {O}_{3}\right)}_{2} \to B a C {l}_{2} + 3 {O}_{2}$

This is called a decomposition reaction and is, essentially, the opposite of a synthesis reaction, i.e. one complex compound breaks down to simpler compounds.

Calcium plus hydrobromic acid

In this reaction, calcium will react with hydrobromic acid in aqueous solution to produce calcium bromide and hydrogen gas

$C {a}_{\left(s\right)} + 2 H B {r}_{\left(a q\right)} \to C a B {r}_{2 \left(a q\right)} + {H}_{2 \left(g\right)}$

Calcium bromide will dissociate in aqueous solution into $C {a}^{2 +}$ and $2 B {r}^{-}$ ions.

Calcium's reaction with hydrobromic acid represents a single replacement reaction; here, calcium, an element, replaces hydrogen in a compound, forming another element, hydrogen, and another compound.