What is the molarity of a solution that contains 0.202 mol KCl in 7.98 L solution?

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

I know the answer to 13 is B and 14 is D. I just need to know why the correct answers are correct

solmaris [256]

In question 13 answer B is the correct one since a catalyst is a chemical that can be added to a reaction to increase the reaction rate without being consumed in the process. In this way, a catalyst accelerates a reaction by decreasing the energy barrier necessary for the reaction to occur or by changing the reaction mechanism. The most common types of catalysts are enzymes, acid base catalysts and heterogeneous catalysts, mostly composed of solids in which the reactants adhere.

In the reaction you have in the question, they use an acid catalyst, H3O+. This catalyst changes the reaction mechanism of 2-butene in 1-butene without being consumed, since it appears at the beginning and at the end of the transformation of 2 butene into 1-butene. The reaction mechanism would be the following

In question 14 the correct answer is option B since the law of velocity of a reaction will be governed by the slow step of the mechanism through which it occurs. In the slow step the chemical species have a harder time transforming because they need more energy to do it, then they will do it in a slower way and the reaction will take longer to occur. Therefore, the slow step is the one that will determine the total speed of the reaction and the speed law must be in terms of that process. The speed of the other two steps is so fast that it is negligible.

5 0

3 years ago

Assume that matter does not consist of atoms. Show by example how this assumption leads to

Leviafan [203]

If matter was not composed of atoms, the law definite proportions and law of multiple proportions will not hold true because compound would have random composition.

<h3>What is the law of definite proportions and law of multiple proportions?</h3>

The law of definite proportions states that all pure samples of a compound contains the same element in a fixed mass ratio.

The law of multiple proportions states that if an element combines with another element to form more than one compound, the mass of the element combines with a fixed mass of the other element in whole number multiples ratios.

Assuming matter was not composed of atoms, the law definite proportions and law of multiple proportions will not hold true because, their will be no definite ratio or composition in compounds.

The law definite proportions and law of multiple proportions are required for the atomic theory as they help prove that matter consists of definite unique particles called atoms.

In conclusion, the existence of atoms is proved true by the law definite proportions and law of multiple proportions.

Learn more about law of multiple proportions at: brainly.com/question/2624012

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4 0

2 years ago

You've just solved a problem and the answer is the mass of an electron, me=9.11×10−31kilograms. How would you enter this number

mihalych1998 [28]

The mass of an electron can be expressed in the box as $\boxed{{m_e} = 9.1 \times {{10}^{ - 31}}{\text{ kg}}}$ .

Further explanation:

Atom is the smallest particle that can be present in any element. It is also known as the building unit of matter. Each atom has a central part that is known as the atomic nucleus. There are three subatomic particles that constitute the atom. These particles are protons, neutrons, and electrons. The atomic nucleus consists of protons and neutrons, both are collectively called nucleons. Electrons revolve around the nucleus of an atom in definite orbits.

Protons are positively charged subatomic particles, electrons are negatively charged and neutrons have no charge. Since electrons carry a unit negative charge, these create an electric field around them. These also participate in nuclear reactions. The mass of an electron $\left( {{m_e}} \right)$ is $9.1 \times {10^{ - 31}}{\text{ kg}}$ , that of protons is $1.6726219 \times {10^{ - 27}}{\text{ kg}}$ and that of neutrons is $1.674927471 \times {10^{ - 27}}{\text{ kg}}$ . The electrons are responsible for chemical properties of elements. The distribution and arrangement of electrons is used to predict whether the element will be inert or reactive.