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3 years ago

How does the Law of Conservation of Mass relate to changes in physical state? How does it relate to chemical changes?

1 answer:

8 0

The Law of Conservation of Mass states that matter cannot be created nor destroyed. It can only be transformed from one state or substance to another. This means that this law applies to both physical and chemical changes. In physical changes, the substance before and after the phase change still has the same mass. In chemical changes, the mass of reactants will always have the same mass of products and by-products.

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Pls help ASAP........ A student was roasting marshmallows over a fire. The student

Phantasy [73]

Answer:

A chemical change

Explanation:

The marshmallow turning brown and bubbling implies that a chemical change has taken place.

For chemical changes to occur, we observe any of the following:

a new kind of matter is formed.
it is always accompanied by energy changes
the process is not easily reversible
it involves a change in mass
requires considerable amount of energy.

ii. Two signs that shows a chemical change has taken place is that:

bubbles are being formed as it is roasted and it implies that new substances have been formed.
also, significant amount of heat energy is supplied for the roasting.

5 0

2 years ago

Which of the following acids is the WEAKEST? The acid is followed by its Ka value.HF, 3.5 × 10^-4HNO2, 4.6 × 10^-4HCN, 4.9 × 10^

Mila [183]

Answer:

HCN

Explanation:

There are several factors that can tell us when an acid is stronger than another, which are the following:

1. The Polarity of the X - H Bond

2. Size of the X atom.

3. Charge on the acid.

4. Oxidation state of the central atom

5. Values of Ka and pKa.

From all of this factors, we can see that the exercise is already giving us values of Ka, and also we have different types of acid, not only with the form H - X

So, we will base the force of an acid by it's pKa value.

The pKa value which is calculated with the expression:

pKa = -logKa

pKa is a value that indicates how strong is the acid you are working with. This value can vary depending on factors such the charge of the acid. I f this charge can be easily distributed in resonance structures, the compound is more acidic, and therefore the pKa value is lower.

The lower the pKa, the more acidic the compound is.

So calculating the pKa on every structure we have:

HF: pKa = -log(3.5x10^-4) = 3.46

HNO2: pKa = -log(4.6x10^-4) = 3.34

HCN: pKa = -log(4.9x10^-10) = 9.31

HCOOH: pKa = -log(1.8x10^-4) = 3.74

HClO2: -log(1.1x10^-2) = 1.96

So according to all this values, we can conclude that the weakest acid is the HCN

4 0

3 years ago

For the of freezing liquid ethanol at a given temperature and pressure,A. ΔH is positive and ΔS is positive.B. ΔH is positive an

Ksivusya [100]

Answer:

ΔH is negative and ΔS is negative.

Explanation:

Endothermic reaction -

The type of reaction in which energy is absorbed in the form of heat is known as endothermic reaction .

The reaction mixture usually get cooled after the reaction .( temperature decreases ) .

The sign of ΔH of an Endothermic reaction is positive .

For the of process of freezing the liquid ethanol , energy in the form of heat is released and hence , exothermic reaction ΔH is negative .

In the process of freezing , liquid is converted to solid , i.e. , the randomness reduces , and hence , entropy also decreases , hence , ΔS is negative .

3 0

3 years ago

The most reactive metals are located at the a)top b)far-left c)far-right d)center of the periodic table.

Jlenok [28]

Answer:

Bottom left corner of the periodic table

Explanation:

The elements toward the bottom left corner of the periodic table are the metals that are the most active in the sense of being the most reactive. Lithium, sodium, and potassium all react with water, for example.

7 0

3 years ago

Read 2 more answers

which process describe water changing from a liquid state to a gas? condensation evaporation infiltration precipitation

Bogdan [553]

evaporation is the process that describe changing of water from liquid to gas

8 0

3 years ago

Read 2 more answers