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3 years ago

Is glass melting a physical or chemical change

Chemistry

1 answer:

Veseljchak [2.6K]3 years ago

6 0

Answer:

No, glass melting is not a chemical reaction. Reactions may bring about change in substances and may be characterized as chemical or physical change.

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What are the three conditions that can cause a chemicl reactions, give examples?<br> Help me plz

finlep [7]

Acid. that’s all i know.

7 0

3 years ago

What is the half-life of a first-order reaction if it takes 4.4 x 102 seconds for the concentration to decrease from 0.50 M to 0

elena55 [62]

Answer: The half-life of a first-order reaction is, $3.3\times 10^2s$

Explanation:

All the radioactive reactions follows first order kinetics.

Rate law expression for first order kinetics is given by the equation:

$k=\frac{2.303}{t}\log\frac{[A_o]}{[A]}$

where,

k = rate constant = ?

t = time taken = 440 s

$[A_o]$ = initial amount of the reactant = 0.50 M

[A] = left amount = 0.20 M

Putting values in above equation, we get:

$k=\frac{2.303}{440s}\log\frac{0.50}{0.20}$

$k=2.083\times 10^{-3}s^{-1}$

The equation used to calculate half life for first order kinetics:

$t_{1/2}=\frac{0.693}{k}$

Putting values in this equation, we get:

$t_{1/2}=\frac{0.693}{2.083\times 10^{-3}s^{-1}}=332.69s=3.3\times 10^2s$

Therefore, the half-life of a first-order reaction is, $3.3\times 10^2s$

4 0

3 years ago

The early hypothesis of _______ was based on observations that suggested continents were once joined together. Later, the theory

zvonat [6]

The early hypothesis of Alfred wegener was based on observations that suggested continents were once joined together. later the theory of plate tectonics explained why large pieces of earths surfaces moves around and how many of earths features form.
but i this case c. continental drift and plate tectonics

6 0

3 years ago

Read 2 more answers

A gas with a volume of 4.0L at a pressure of 205kPa is allowed to expand to a volume of 12.0L. What is the pressure in the conta

mr Goodwill [35]

Answer:

68.3 kilo Pascal is the pressure in the container.

Explanation:

To calculate the new pressure , we use the equation given by Boyle's law. This law states that pressure is inversely proportional to the volume of the gas at constant temperature.

The equation given by this law is:

$P_1V_1=P_2V_2$

where,

$P_1\text{ and }V_1$ are initial pressure and volume.

$P_2\text{ and }V_2$ are final pressure and volume.

We are given:

$P_1=205kPa\\V_1=4.0 L\\P_2=?\\V_2=12.0 L$

Putting values in above equation, we get:

$P_2=\frac{P_1V_1}{V_2}$

$=\frac{205 kPa\times 4.0 L}{12.0 L}=68.3 kPa$

68.3 kilo Pascal is the pressure in the container.

5 0

3 years ago

The phenolic indicator (In-OH)has approximately the same pKa as a carboxylic acid. Which H is the most acidic proton in In-OH? C

Sidana [21]

The –OH+ group is most acidic proton in ln-OH as shown in figure (a). The proton is circled in the figure.

The stabilisation of the conjugate base produced is stabilises due to resonance factor. The possible resonance structures are shown in figure (b).

The acidity of a protonated molecule depends upon the stabilisation of the conjugate base produced upon deprotonation. The conjugate base of ln-OH is shown in figure (a).

The possible resonance structures are shown in figure (b). As the number of resonance structures of the conjugate base increases the stabilisation increases. Here the unstable quinoid (unstable) form get benzenoid (highly stable) form due to the resonance which make the conjugate base highly stabilise.

Thus the most acidic proton is assigned in ln-OH and the stability of the conjugate base is explained.

4 0

3 years ago