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2 years ago

If a person burns 2171 Cal each day, how much energy (kJ) does she burn in 2 days??

Chemistry

1 answer:

Nataly_w [17]2 years ago

7 0

As 1 calorie = 4.184 jouls

1 calorie = 0.004184 kilojouls

Total calories for two days = 2171 x 2 = 4342 calories

Hence the energy in kj = 4342 x 0.004184 = 18.16 kj

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Give the nuclide symbol for an atom that has mass number 64 and 35 neutrons.

azamat

The mass number represents the summation of the number of protons and the number of neutrons in the nucleus of an atom.
We are given that the mass number is 64 and that the number of neutrons is 35. Therefore:
number of protons = 64 - 35 = 29 protons

In ground state, number of protons in an atom is equal to the number of electrons. Therefore,
number of electrons = 29 electron

Using the periodic table, we will find that the element that has 29 electrons in ground state is copper.
The nuclide symbol of copper is shown in the attached image.

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2 years ago

A 150 W electric heater operates for 12.0 min to heat an ideal gas in a cylinder. During this time, the gas expands from 3.00 L

Brut [27]

Answer: The change in internal energy of the gas is 108.835 kJ

Explanation:

To calculate the work done for reversible expansion process, we use the equation:

$W=P\Delta V=-P(V_2-V_1)$

where,

W = work done

P = pressure = 1.03 atm

$V_1$ = initial volume = 3.00 L

$V_2$ = final volume = 11.0 L

Putting values in above equation, we get:

$W=-(1.03)\times (11.0-3.00)=8.24L.atm=834.9J=0.835kJ$ (Conversion factor: 1 L. atm = 101.325 J)

Calculating the heat from power:

$Q=P\times t$

where,

Q = heat required

P = power = 150 W

t = time = 12 min = 720 s (Conversion factor: 1 min = 60 s)

Putting values in above equation:

$Q=150\times 720=108000J=108kJ$

The equation for first law of thermodynamics follows:

$Q=dU+W$

where,

Q = total amount of heat required = 108 kJ

dU = Change in internal energy = ?

W = work done = -0.835 kJ

Putting values in above equation, we get:

$108kJ=dU+(-0.835)\\\\dU=(108+0.835)=108.835kJ$

Hence, the change in internal energy of the gas is 108.835 kJ

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2 years ago

A student noticed a yellow, solid substance was formed when mixing two clear liquids during a lab. What term describes this yell

givi [52]

Answer:

Explanation:

a precipitate is formed from a solution

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2 years ago

What is the name of the compound CuCO³?

Tems11 [23]

Basic copper carbonate

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2 years ago

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C5H12, pentane, is a liquid at room temperature.

Art [367]

Answer:

C)We cannot be sure unless we find out its boiling point.

Explanation:

It is necessary to clearly explain here that simply observing two compounds of the same homologous series irrespective of how close they may be in the series will not give us the faintest idea regarding which one will be a liquid, solid or gas at room temperature.

However, to determine whether an unknown substance will be a liquid at room temperature, then its important to measure its boiling point. If the boiling point is above room temperature, and the melting point is below room temperature, the compound is a liquid. If the boiling point of the unknown substance is below room temperature, it is a gas.

It is now safe to conclude that cannot decide on the state of matter in which a compound exists unless we know something about its boiling point, not merely looking closely at the properties of its neighbouring compounds in the same homologous series

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2 years ago