During the early paleozoic land plants begin to grow which consisted of

Find the energy required to melt the copper once it's reached the melting point.

belka [17]

The answer has to depend on the mass of the copper that you're trying to melt.

But there is a formula which you can calculate the energy required if you have the information of the mass. This formula requires the value called specific latent heat of fusion, which is the energy required to melt or freeze a specific mass of copper without changing its temperature but change its state.
$E = m l_{f}$
E is the total energy required, m is the mass, and lv is the specific latent heat of fusion of copper.

Usually, in questions, lv is given. But we can also look it up online which is around 205kJ kg^-1
this means, to melt or freeze a copper, we need to work the mass multiplied by 205kJ in order to calculate its total energy needed or released.

8 0

3 years ago

A gas has a volume of 300 mL in a rigid container at 50oC and 1.75 atm. What will be its pressure at 100K?

eduard

Answer:

Its pressure will be 0.54 atm at 100 K.

Explanation:

Gay-Lussac's law indicates that, as long as the volume of the container containing the gas is constant, as the temperature increases, the gas molecules move faster. Then the number of collisions with the walls increases, that is, the pressure increases. That is, the pressure of the gas is directly proportional to its temperature.

Gay-Lussac's law can be expressed mathematically as the quotient between pressure and temperature equal to a constant:

$\frac{P}{T} =k$

Studying two different states, an initial state 1 and a final state 2, it is satisfied:

$\frac{P1}{T1} =\frac{P2}{T2}$

In this case:

P1= 1.75 atm
T1= 50 °C= 323 K (being 0 C=273 K)
P2= ?
T2= 100 K

Replacing:

$\frac{1.75 atm}{323 K} =\frac{P2}{100 K}$

Solving:

$P2= 100 k*\frac{1.75 atm}{323 K}$

P2= 0.54 atm

Its pressure will be 0.54 atm at 100 K.

8 0

3 years ago

During an experiment, 104 grams of calcium carbonate reacted with an excess amount of hydrochloric acid. If the percent yield of

postnew [5]

Answer:

92.4 grams.

Explanation:

From the balanced reaction:

CaCO₃ + 2HCl → CaCl₂ + CO₂ + H₂O,

1.0 mole of CaCO₃ reacts with 2.0 moles of HCl to produce 1.0 mole of CaCl₂, 1.0 mole of CO₂, and 1.0 mole of H₂O.

We need to calculate the no. of moles of (104 g) of CaCO₃:

no. of moles of CaCO₃ = mass/molar mass = (104 g)/(100.08 g/mol) = 1.039 mol.

Using cross multiplication:

1.0 mole of CaCO₃ produce → 1.0 mole of CaCl₂.

∴ 1.039 mole of CaCO₃ produce → 1.039 mole of CaCl₂.

∴ The amount of CaCl₂ produced = no. of moles x molar mass = (1.039 mol)(110.98 g/mol) = 114.3 g.

∵ percent yield of the reaction = [(actual yield)/(theoretical yield)] x 100.

Percent yield of the reaction = 80.15%, theoretical yield = 115.3 g.

∴ actual yield = [(percent yield of the reaction)(theoretical yield)]/100 = [(80.15%)/(115.3 g)] / 100 = 92.42 g ≅ 92.4 g.

7 0

3 years ago

In the following reaction, how many moles of FeO are needed to react completely with 1.6 mol of Al? 1.2 1.8 2.4 3.0

alexgriva [62]

I’m not

Sure I’m sorry

4 0

3 years ago

Based upon the valence electrons as taken from the periodic table, the formula for rubidium (Rb) chloride (Cl) is:

kati45 [8]

Rubidium (Rb) is in group 1, so it has a valence charge of +1.
Chlorine (Cl) is in group 17 or the halogens, so it has a valence charge of -1.

Since both elements have the same valence charges, just of opposite signs, this means that only 1 atom of each element is needed to create a stable bond. The formula for rubidium chloride will be RbCl.

7 0

3 years ago