When ice melts, the physicals state changes from solid to liquid. The energy or the heat required (q) required to change a unit mass (m) of a substance from solid to liquid is known as the enthalpy or heat of fusion (ΔHf). The variables; q, m and ΔHf are related as:
q = m * ΔHf
the mass of ice m = 65 g
the heat of fusion of water at 0C = ΔHf = 334 J/g
Therefore: q = 65 g * 334 J/g = 21710 J
Now:
4.184 J = 1 cal
which implies that: 21710 J = 1 cal * 21710 J/4.184 J = 5188.8 cal
Hence the heat required is 5188.8 cal or 5.2 Kcal (approx)
Answer:
C. The species became more resistant to the insecticide.
Explanation:
The more of something you receive, the more immune you are to it. For example, every year, many people get a flu shot. Flu shots contain small amounts of the flu, and it is inserted into your blood stream so that you may become more immune to the disease when it comes around. The same happens for many living things, including insects.
w/w percentage <span>
= mass of the pure compound /
total mass of the sample x 100%
70% HNO₃
contains by mass means every 100 g of sample has 70 g of HNO₃.</span><span>
The mass of solution = 103.8 g
Hence the mass of HNO₃ = 103.8 g x 70%</span><span>
= 103.8 g x (70 / 100)
<span>
= 72.66 g = 72.7 g.</span></span>
Answer:
It is required answer.
Explanation:
Given that :
1. using balanced chemical equation:
ammonium acetate:
The balanced equation is:
NH₃ + H₂O ===> NH₄OH
when ammonia gas dissolves in water then we get the base in form of ammonium hydroxide.
When NH₄OH reacts with CH₃COOH then we get ammonium acetate and water
NH₄OH + CH₃COOH ===> [CH₃COO]- & NH₄+ & H₂O
So, we can say that,
when we are adding an acid and a base together then we get the product of H₂O and given elements.
2. addition of barium hydroxide to sulfuric acid:
the balanced equation is
H₂SO4+ Ba(OH)₂--> BaSO₄+ 2H₂O
when acid and base reacts together than we get barium sulphate and water
when sulfuric acid and barium hydroxide.
Hence, it is required answer.
The best and most correct answer among the choices provided by your question is the third choice or letter C.
The best model of a water <span>molecule would be: </span><span>Two small, plastic balls attached to a larger plastic ball by toothpicks</span>
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