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nlexa [21]
2 years ago
15

Standard Heat of Formation: The enthalpy change for the formation of 1 mol of a substance in its standard state from its constit

uent elements in their standard states. True/ false?
Chemistry
1 answer:
12345 [234]2 years ago
6 0

The given statement about standard heat of formation is true.

Explanation:

Yes, it is true that standard heat of formation is same as standard enthalpy of formation. As enthalpy is termed for change in the heat energy occurred in the process of completion of any chemical reaction, the standard enthalpy or heat of formation is termed as the heat energy required to form 1 mole of any substance in its standard state from its original, parent or constituent elements in their standard state. Basically, it defines the amount of energy required by the system or compound for its formation from different elements under different synthesis conditions but the nature of the parent samples and temperature and pressure should be kept standard.

So the given statement is true.

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A vessel of volume 22.4 dm3 contains 20 mol h2 and 1 mol n2 ad 273.15 k initially. All of the nitrogen reacted with sufficient h
NikAS [45]

Nitrogen combine with hydrogen to produce ammonia \text{NH}_3 at a 1:3:2 ratio:

\text{N}_2 \; (g) + 3 \;  \text{H}_2 \; (g) \leftrightharpoons 2\; \text{NH}_3 \; (g)

Assuming that the reaction has indeed proceeded to completion- with all nitrogen used up as the question has indicated. 3 \; \text{mol} of hydrogen gas would have been consumed while 2 \; \text{mol} of ammonia would have been produced. The final mixture would therefore contain

  • 17 \; \text{mol} of \text{H}_2 \; (g) and
  • 2 \; \text{mol} of \text{NH}_3 \; (g)

Apply the ideal gas law to find the total pressure inside the container and the respective partial pressure of hydrogen and ammonia:

  • \begin{array}{lll} P(\text{container}) &= & n \cdot R \cdot T / V \\ & = & (17 + 2) \; \text{mol} \times 8.314 \; \text{L} \cdot \text{kPa} \cdot \text{mol}^{-1} \cdot \text{K}^{-1} \\ & &\times 273.15 \; \text{K} / (22.4 \; \text{L}) \\ &=&  1.926 \times 10^{3} \; \text{kPa} \end{array}
  • \begin{array}{lll} P(\text{H}_2) &= & n \cdot R \cdot T / V \\ & = & (17) \; \text{mol} \times 8.314 \; \text{L} \cdot \text{kPa} \cdot \text{mol}^{-1} \cdot \text{K}^{-1} \\ & &\times 273.15 \; \text{K} / (22.4 \; \text{L}) \\ &=&  1.723 \times 10^{3} \; \text{kPa} \end{array}
  • \begin{array}{lll} P(\text{NH}_3) &= & n \cdot R \cdot T / V \\ & = & (2) \; \text{mol} \times 8.314 \; \text{L} \cdot \text{kPa} \cdot \text{mol}^{-1} \cdot \text{K}^{-1} \\ & &\times 273.15 \; \text{K} / (22.4 \; \text{L}) \\ &=&  2.037 \times 10^{2} \; \text{kPa} \end{array}
6 0
3 years ago
The half-life for the radioactive decay of C-14C-14 is 5730 years. You may want to reference (Pages 598 - 605) Section 14.5 whil
KIM [24]

<u>Answer:</u> The sample of Carbon-14 isotope will take 2377.9 years to decay it to 25 %

<u>Explanation:</u>

The equation used to calculate rate constant from given half life for first order kinetics:

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

where,

t_{1/2} = half life of the reaction = 5730 years

Putting values in above equation, we get:

k=\frac{0.693}{5730yrs}=1.21\times 10^{-4}yrs^{-1}

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  = 1.21\times 10^{-4}yr^{-1}

t = time taken for decay process = ? yr

[A_o] = initial amount of the sample = 100 grams

[A] = amount left after decay process =  (100 - 25) = 75 grams

Putting values in above equation, we get:

1.21\times 10^{-4}=\frac{2.303}{t}\log\frac{100}{75}\\\\t=2377.9yrs

Hence, the sample of Carbon-14 isotope will take 2377.9 years to decay it to 25 %

8 0
3 years ago
Explain the process of groundwater
Anon25 [30]

Answer:

Limestone is easily eroded from above and below.

Explanation:

The Florida bedrock is largely made of limestone. Because limestone is a rock that is easily eroded, the landscape of a great part of Florida is classified as karstic.

Karstic landscapes are dotted by sinkholes, underground rivers, caves, and springs. The more acidic the groundwater or rainwater, the faster and more easily the limestone will succumb to erosion.

In this way, underground rivers, streams, runoff, rain, and underground water pooled in caves have all carved out gaps and caverns in the weak limestone bedrock.

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2 years ago
Which of the following are testable?
jeyben [28]

you forgot the well answers

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2 years ago
Read 2 more answers
Which statement describes a chemical property of water?
anygoal [31]
<span>The chemical description of water is H2O, which means, it is composed of 2 hydrogen atoms and 1 oxygen atom. The answer to this item is the fourth option, " It is clear and colorless." When water is added with calcium, clear, colorless bubbles are formed. This explains a reaction of water with acid. The following are additional facts about water properties: Density: 1 g/cm³ Boiling point: 100 °C Molar mass: 18.01528 g/mol Melting point: 0 °C Formula: H2O</span>
7 0
2 years ago
Read 2 more answers
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