7. D. 668 joules
8. B. 3 grams
<h3>Further explanation</h3>
Given
2 grams of water
6768 joules of energy
Required
Energy
Mass of water
Solution
The heat to change the phase can be formulated :
Q = m.Lf (melting/freezing)
Q = m.Lv (vaporization/condensation)
Lf=latent heat of fusion
Lv=latent heat of vaporization
7. phase change (ice to water)⇒Heat of fusion water=334 J/g
Q = 2 g x 334 J/g
Q = 668 J
8. phase change(water to vapor)⇒heat of vaporization water=2260 J/g
6768 J = m x 2260 J/g
m = 3 g
<h3>
Answer:</h3>
- Balanced Equation; 2Fe + 3H₂SO₄ → Fe₂(SO₄)₃ + 3H₂
- Why balance?: To obey the law of conservation of mass
- Subscripts can not be changed, since they show the actual number of atoms of each element in a compound.
<h3>
Explanation:</h3>
- The balanced equation for the reaction between the iron metal and sulfuric acid to produces iron (III) sulfate and hydrogen gas is given by;
2Fe + 3H₂SO₄ → Fe₂(SO₄)₃ + 3H₂
- Balancing chemical equations ensures that they obey the law of conservation of mass which requires the mass of reactants and the mass of products to be equal.
- Balancing is done by putting coefficients on reactants and products while not affecting the subscripts as subscripts show the actual number of atoms of an element in a compound.
Answer:
1. 3CaCrO4
2. 6
3. 3
Explanation:
1. Reactans on left side, products on right side
2. 3 x 2
3. 3
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