How much heat energy (in megajoules) is needed to convert 7 kilograms of ice at –9°C to water at 0°C?

1 answer:

8 0

The heat required to change the phase of a substance can be calculated by using the formula,

q = mCΔT where q is the heat needed, m is the mass of the substance, C is the specific heat capacity and ΔT is the change in temperature.

q = 7000 g (4.18 J/ g °C) (0°C - (-9°C))
q = 263340 J or .26334 MJ
Hope it's correct! ( If so rank as brainliest answer) :)

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Suppose two point charges, Q1 = -6.25 x 10-9 C and Q2 = -6.25 x 10-9 C, are separated by a distance d = 0.617 m.

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Answer:

The answer to your question is the letter A) F = 9.23 x 10⁻⁷ N

Explanation:

Data

q₁ = -6.25 x 10⁻⁹ C

q₂ = -6.25 x 10⁻⁹ C

d = 0.617 m

k = 9 x 10⁹ Nm²/C²

F = ?

Formula

F = k q₁q₂ /r²

-Substitution

F = (9 x 10⁹)(-6.25 x 10⁻⁹)(-6.25 x 10⁻⁹) / (0.617)²

-Simplification

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