Use these equations to you answer the questions.

change in thermal energy (j) = mass (kg) x specific heat capacity (j/kg/°c) x
change in temperature (°c)

thermal energy needed for a change of state (j) = mass (kg) x specific latent heat (j/kg)

q1. some students have 100 g of ice. the temperature of the ice
nave 100 g of ice. the temperature of the ice is -4 °c. they need to calculate how much energy
they will need to heat the ice until it is all melted.
first they calculate how much energy is needed to heat the ice to its melting point. write down the equation
they use to do this.

(1 mark)

q2. next they calculate how much energy is needed to melt the ice. write down the equation they use to
do this.

(1 mark)

Aheat engine running backward is called a refrigerator if its purpose is to extract heat from a cold reservoir. the same engine running backward is called a heat pump if its purpose is to exhaust warm air into the hot reservoir. heat pumps are widely used for home heating. you can think of a heat pump as a refrigerator that is cooling the already cold outdoors and, with its exhaust heat qh, warming the indoors. perhaps this seems a little silly, but consider the following. electricity can be directly used to heat a home by passing an electric current through a heating coil. this is a direct, 100% conversion of work to heat. that is, 19.0 \rm kw of electric power (generated by doing work at the rate 19.0 kj/s at the power plant) produces heat energy inside the home at a rate of 19.0 kj/s. suppose that the neighbor's home has a heat pump with a coefficient of performance of 4.00, a realistic value. note: with a refrigerator, "what you get" is heat removed. but with a heat pump, "what you get" is heat delivered. so the coefficient of performance of a heat pump is k=qh/win. an average price for electricity is about 40 mj per dollar. a furnace or heat pump will run typically 200 hours per month during the winter. what does one month's heating cost in the home with a 16.0 kw electric heater? what does one month's heating cost in the home of a neighbor who uses a heat pump to provide the same amount of heating?

How is an electron dot structure used to represent a covalent bond?

Why is a noble gas different from other elements