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Svetradugi [14.3K]
2 years ago
8

Does seeing a gas produced always mean a chemical reaction is occurring? Explain.

Chemistry
2 answers:
chubhunter [2.5K]2 years ago
4 0
Seeing signs of a chemical reaction does not always mean that a reaction is happening. For example, a gas (water vapor) is given off when water boils. ... You can tell that it is a physical change because water vapor can condense to form liquid water. In a chemical change, a new substance must be produced.
Alex17521 [72]2 years ago
4 0

Answer:

Explanation:

yes

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Calculate the standard entropy of vaporization of ethanol at its boiling point, 352 K. The standard molar enthalpy of vaporizati
Korvikt [17]

Answer : The correct option is, (b) +115 J/mol.K

Explanation :

Formula used :

\Delta S=\frac{\Delta H_{vap}}{T_b}

where,

\Delta S = change in entropy

\Delta H_{vap} = change in enthalpy of vaporization = 40.5 kJ/mol

T_b = boiling point temperature = 352 K

Now put all the given values in the above formula, we get:

\Delta S=\frac{\Delta H_{vap}}{T_b}

\Delta S=\frac{40.5kJ/mol}{352K}

\Delta S=115J/mol.K

Therefore, the standard entropy of vaporization of ethanol at its boiling point is +115 J/mol.K

8 0
3 years ago
Drawing a conclusion derived from knowledge of an established principle is called deductive reasoning.
allsm [11]

Answer:

the answer would be true

8 0
3 years ago
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Calculate the ph of a solution containing 0.0451 m potassium hydrogen tartrate and 0.028 m dipotassium tartrate. The ka values f
Marina86 [1]

Given buffer:

potassium hydrogen tartrate/dipotassium tartrate (KHC4H4O6/K2C4H4O6 )

[KHC4H4O6] = 0.0451 M

[K2C4H4O6] = 0.028 M

Ka1 = 9.2 *10^-4

Ka2 = 4.31*10^-5

Based on Henderson-Hasselbalch equation;

pH = pKa + log [conjugate base]/[acid]

where pka = -logKa

In this case we will use the ka corresponding to the deprotonation of the second proton i.e. ka2

pH = -log Ka2 + log [K2C4H4O6]/[KHC4H4O6]

     = -log (4.31*10^-5) + log [0.0451]/[0.028]

pH = 4.15



4 0
3 years ago
A sample of carbon of mass 250 mg from wood found in a tomb underwent 2480 carbon- 14 disintegrations in 20 h. Estimate the time
Ksenya-84 [330]

Explanation:

Let the age to be found in years is y.

Hence,       (2480 disintegrations) \times \frac{\frac{1.0g}{0.250g}}{1.84 \times 10^{4} disintegrations}

                        = (\frac{1}{2})^{\frac{y}{5730yr}}

Solve for y as follows.

                    0.53913 = (\frac{1}{2})^{\frac{y}{5730yr}}

Now, taking log on both the sides as follows

               log 0.53913 = (\frac{z}{5730}) log \frac{1}{2}


               \frac{log 0.53913}{log (1/2)} = \frac{z}{5730}

                       z = \frac{5730 \times log 0.53913}{log (1/2)}

                         = 5107 years

Thus, we can conclude that the time since death is 5107 years.

5 0
3 years ago
At room temperature, a melting solid produces a whitish liquid. A laser beam shined through the liquid is unaffected and produce
stiks02 [169]
The liquid is a heterogeneous.
4 0
3 years ago
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