# Repaint a fox

Probably, there is no such a schoolboy who would not have read with enthusiasm the remarkable fairy tale of I.Ya. Franco "The painted fox". It turns out, to **repaint a fox** it is possible and without paint.

An experience. On a thick white paper, draw a fox and cut out the drawing with scissors. In a beaker, a saturated solution of K_{2}Cr_{2}O_{7} in dilute H_{2}SO_{4}. White fox completely immersed in this solution - it becomes red. The wet fox is thrown into a large beaker, filled with gaseous SO_{2} before the time. The stuffy **sulfur gas** acts on the red fox and it quickly turns blue or blue. Such a metamorphosis is due to the oxidation-reduction transformation. This produces a chromo-calcium galloon:

_{2}Cr

_{2}O

_{7}(îðàíæåâûé) + 3SO

_{2}+ Í

_{2}SO

_{4}+ 23Í

_{2}O = 2ÊCr(SO

_{4})

_{2}*12Í

_{2}O(ñèíèé).

The most easily sulfuric gas can be obtained due to the interaction of concentrated H_{2}SO_{4} with copper chips or Na_{2}SO_{3} (slightly moistened with water). The reactions are carried out under mild heating:

_{2}SO

_{4}= ÑuSO

_{4}+ 2Í

_{2}O + SO

_{2};

_{2}SO

_{3}+ 2Í

_{2}SO

_{4}= 2NàÍSO

_{4}+ Í

_{2}O + SO

_{2}.