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3 years ago

How much energy must be added to a 2-kg piece of wood with a specific heat

Chemistry

1 answer:

lesya692 [45]3 years ago

6 0

Answer:

A. 140,800 J

Explanation:

Specific heat of a material is defined as the amount of energy required to increase in 1°C 1kg of the material. For wood there are required 1760J perkg per °C.

The equation is:

Q = C*m*ΔT

Where Q is heat in Joules,

C is specific heat (1760J/kg°C),

m is mass (2kg)

ΔT is change in temperature (50°C - 10°C = 40°C)

Replacing:

Q = 1760J/kg°C*2kg*40°C

Q = 140800J

Right option is:

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Is a flashlight turned on kinetic or potential energy ?

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Answer: potential energy

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3 years ago

There are two steps in the extraction of copper metal from chalcocite, a copper ore. In the first step, copper(I) sulfide and ox

maxonik [38]

Answer:

2Cu2S + 3O2 + 2C -------> 4Cu + 2SO2 + 2CO

Explanation:

Equation 1 should correctly be written as;

2Cu2S + 3O2-----> 2Cu2O + 2SO2

Equation 2 should be correctly written as;

2Cu2O + 2C -----> 4Cu + 2CO

The overall reaction equation is;

2Cu2S + 3O2 + 2C -------> 4Cu + 2SO2 + 2CO

Note that species that are intermediates are cancelled out .

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2 years ago

Another carbon isotope has six protons and seven neutrons in its nucleus. What do you think this carbon isotope is called?

insens350 [35]

Answer:

Carbon - 13

Explanation:

For most of the elements other than that of hydrogen, the isotopes are named for the mass number.

Example : Carbon atoms with 6 neutrons have mass number of 12 ( as $6\ protons +6\ neutrons=12$ ), so they are known as carbon-12.

Given that:

Protons = 6

Neutrons = 7

Mass = 6 + 7 = 13

So the name is Carbon - 13 . The symbol is $^{13}_{6}C$

8 0

3 years ago

Read 2 more answers

Qu 4.

Anna11 [10]

Answer:

It's the second one down.

Explanation:

Gold

Mass 197

Number of Protons: 79

Number of Neutrons: 197 - 79 = 118

Number of electrons: = number of protons = 97

3 0

3 years ago

The vapor above a mixture of pentane and hexane at room temperature contains 35.5% pentane by mass. What is the mass percent com

FrozenT [24]

The mass percent of Pentane in solution is 16.49%

The mass percent of Hexane in solution is 83.51%

Explanation:

Take 1 kg basis for the vapor: 35.5 mass% pentane = 355 g pentane with 645 g hexane.

Convert these values to mol% using their molecular weights:

Pentane: Mp = 72.15 g/mol -> 355g/72.15 g/mol = 4.92mol

Hexane: Mh = 86.18 g/mol -> 645g/86.18 g/mol = 7.48mol

Pentane mol%: yp = 4.92/(4.92+7.48) = 39.68%

Hexane mol%: yh = 100 - 39.68 = 60.32%

Pp-vap = 425 torr = 0.555atm

Ph-vap = 151 torr = 0.199atm

From Raoult's law we know:

Pp = xp $\times$ Pp - vap = yp $\times$ Pt (1)

Ph = xh $\times$ Ph - vap = yh $\times$ Pt (2)

Since it is a binary mixture we can write xh = (1 - xp) and yh = (1 - yp), therefore (2) becomes:

(1 - xp) $\times$ Ph - vap = (1 - yp) $\times$ Pt (3)

Substituting (1) into (3) we get:

(1-xp) $\times$ Ph - vap = (1 - yp) $\times$ xp $\times$ Pp - vap / yp (4)

Rearrange for xp:

xp = Ph - vap / (Pp - vap/yp - Pp - vap + Ph - vap) (5)

Subbing in the values we find:

Pentane mol% in solution: xp = 19.08%

Hexane mol% in solution: xh = 80.92%

Now for converting these mol% to mass%, take 1 mol basis for the solution and multiplying it by molar mass:

mp = 0.1908 mol $\times$ 72.15 g/mol

= 13.766 g

mh = 0.8092 mol $\times$ 86.18 g/mol

= 69.737 g

Mass% of Pentane solution = 13.766/(13.766+69.737)

= 16.49%

Mass% of Hexane solution = 83.51%

8 0

3 years ago