#1: The element that loses electrons in a chemical reaction is said to have been which of the following?
A. reduced
B. oxidized
C. combusted
D. rusted
**idk, is it reduced or oxidized??
Answer: oxidized. The element that loses electrons increases its oxidation number (becomes more positve or less negative) and this is oxidation.
Which type of reaction occurs if one element gains electrons and another loses electrons?
A. combustion
B. synthesis
C. oxidation-reduction
D. double-displacement
**my answer: C
Yes, oxidation-reduction
#3: What is the oxidation number for phosphorus in H4P2O7?
A. +5
B. +3
C. +1
D. - 1
**my answer: A. +5
This is the way to calculate it 4(+1) + 2x + 7(-2) = 0 => x = +5
#4: What is the oxidation number for phosphorus in Na2HPO3?
A. +5
B. +3
C. +1
D. - 1
**my answer; B. +3
is that right??
Right
2(+1) + 1 + x + 3(-2) = 0 => x = 6 -1 -2 = 3 (positive)
When the enthalpy value is given, we can calculate how much heat is use or produces in a given equation.
67.6 kCal ---> 67.6 kCal= 1 mol of reaction
1 mol of reaction= 1 mol of CO (based on the coefficient)
so 1 mole of CO gives us 67.6 kCal of heat.
calculation:
1 mol CO
Answer:
Explanation:
Here we have to use stoichiometry.
First of all, we have to calculate the mass of 100% of yield:
1.7 g ------- 98%
X -------- 100%
X = 1.73 g (approximately)
Second, we have to calculate the mass of N2 that is necessary to react to produce the mass of 1.73g of NH3. To do that, we have to use the Molar mass of N2 and NH3 and don't forget the stoichiometric relationship between them.
Molar Mass N2 : 14x2 = 28 g/mol
Molar Mass NH3: 14 + 3 = 17 g/mol
28g (N2) ------- 17x2 (NH3)
X ------------ 1.73 g
X = 1.42 g (approximately)
