The mass of magnesium should be less than 0.09g to enable a faster reaction rate. Magnesium reacts to form a white coating around it which stops the reaction. The lesser the gram the faster the reaction before the coating is formed. It is also advisable to use magnesium fillings to increase the rate of reaction.
Answer:
C
Explanation:
Reduction can be seen through addition (gaining) of electrons, addition of Hydrogen or removal of Oxygen
Mn7+ is reduced to Mn4+ by the addition of 3 electrons.
1.Calculate the number of mole of O2: 48/32=1.5 mol
2.Calculate the number of mole of H2 by mole ratio: 1.5 x 1/2=0.75 mol
3.Calculate the answer:
0.75 x 2=1.5g
Number of photons can be calculated by dividing the needed energy by the energy per photon.
The minimum energy needed is given as 2 x 10^-17 joules
Energy per photon = hc / lambda where h is planck's constant, c is the speed of light and lambda is the wavelength
Energy per photon = (<span>6.626 x 10^-34 x 3 x 10^8) / (475 x 10^-9)
= 4.18 x 10^-19 J
number of photons = (2 x 10^-17) / (4.18 x 10^-19)
= 47.79 photons which is approximately 48 photons</span>
Answer:
+2.5
Explanation:
So the oxidation number of S in Na2S4O6is +2.5.
