Answer:
Reducing sugars are absent
Explanation:
Benedict's solution is an substance used in testing sugars. It is mixture of sodium carbonate, sodium citrate and copper(II) sulfate pentahydrate. It can be used instead of Fehling's solution in testing for the presence of reducing sugars.
Reducing sugars contain the -CHO group. If there is no colour change after the addition of Benedict's solution, then we can conclude that reducing sugars are absent.
The values of x represents that number of moles of water molecules that is present per mole of the salt magnesium sulfate. To determine the value for this, we need to know how much is the water that is lost after heating the sample assuming that all of the water molecules are evaporated leaving only the unhydrated form of the salt. We calculate as follows:
Mass of hydrated salt = 3.484 g
Mass after heating = 1.701 g
Mass lost = 3.484 g - 1.701 g = 1.783 g
The mass lost is equal to the mass of water lost.
Moles water lost = 1.783 g ( 1 mol / 18.02 g ) = 0.0989 mol H2O
Moles of unhydrated salt = 1.701 g ( 1 mol / 120.37 g ) = 0.0141 mol MgSO4
moles water / moles MgSO4 = 0.0989 mol H2O / 0.0141 mol MgSO4 = 7
Therefore, the value of x is 7.
Answer:
An exothermic reaction is a chemical reaction in which less energy is needed to break bonds in the reactants than is released when new bonds form in the products. During an exothermic reaction, energy is constantly given off, often in the form of heat. All combustion reactions are exothermic reactions.
Explanation:
