First you need to find the number of moles there are in 89g of Mg(NO₃)₂ . To do this, divide the 89g by the molar mass of magnesium nitrate (148.3g/mol) to get 0.6mol of magnesium nitrate. Then to find the volume of solution that contains 0.6 moles you need to divide 0.6mol by 0.40M to get 1.5L of solution.
I hope this helps. Let me know in the comments if anything is unclear.
C. fluorescence.
Because it refers to the release of light.
I believe the answer would be B
The answer is: Cl was reduced in this reaction
according to the balanced reaction equation, we can know that:
- as Cl in OCl^- is +1
and Cl in Cl^- is -1
- and Cr in CrO4^-2 is +6
- and Cr in Cr(OH)3 is +3
∴ Cl went from +1 to -1 and was reduced, It means a reduction in charge.
& Cr went from +3 to +6 so it was oxidized.
Empirical formula is the simplest ratio of components making up a compound.
The percentage composition of each element has been given
therefore the mass present of each element in 100 g of compound is
B N H
mass 40.28 g 52.20 g 7.53 g
number of moles
40.28 g / 11 g/mol 52.20 g / 14 g/mol 7.53 g / 1 g/mol
= 3.662 mol = 3.729 mol = 7.53 mol
divide the number of moles by the least number of moles, that is 3.662
3.662 / 3.662 3.729 / 3.662 7.53 / 3.662
= 1.000 = 1.018 = 2.056
the ratio of the elements after rounding off to the nearest whole number is
B : N : H = 1 : 1 : 2
therefore empirical formula for the compound is B₁N₁H₂
that can be written as BNH₂