Answer:
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Answer:
-68.4 kJ
Explanation:
The standard enthalpy of vaporization = 23.3 kJ/mol
which means the energy required to vaporize 1 mole of ammonia at its boiling point (-33 °C).
To calculate heat released when 50.0 g of ammonia is condensed at -33 °C.
This is the opposite of enthalpy of vaporization which means that same magnitude of heat is released.
Thus, Q = -23.3 kJ/mol
Where negative sign signifies release of heat
Given: mass of 50.0 g
Molar mass of ammonia = 17.034 g/mol
Moles of ammonia = 50.0 /17.034 moles = 2.9353 moles
Also,
1 mole of ammonia when condenses at -33 °C releases 23.3 kJ
2.9412 moles of ammonia when condenses at -33 °C releases 23.3×2.9353 kJ
Thus, amount of heat released when 50 g of ammonia condensed at -33 °C= -68.4 kJ, where negative sign signifies release of heat.
The heat released when 50.0 g of ammonia condenses at its boiling point is -68.4 kJ. This is calculated by multiplying the moles of ammonia by the enthalpy of vaporization and recognizing that heat is released in condensation.
To solve this problem, we need to understand the concept of enthalpy of vaporization, which is the heat needed to convert 1 mole of a substance from a liquid to a gas at constant pressure and temperature. For ammonia (NH3), which boils at -33 °C, the enthalpy of vaporization is 23.3 kJ/mol. However, we want the heat released when 50.0 g (around 2.94 moles) of ammonia condenses, which is the reverse process of vaporization. Thus, the energy would be released rather than absorbed.
Now, let's calculate this value. We multiply the number of moles of ammonia by the enthalpy of vaporization:
2.94 moles x 23.3 kJ/mol = 68.4 kJ
Since this is the reverse of the process of vaporization, heat is released, so the enthalpy change is negative (-68.4 kJ). Therefore, the correct answer is -68.4 kJ.
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(b) Analysis of the nitrate content of soil near a local water source. soil nitrate
(c) Measurement of the citric acid found in a lime.
Identify the following as either sample or analyte.
(1) lead
(2) paint chips
(3) soil
(4) nitrate
(5) lime wedge
(6) citric acid
Answer:
a) Analyte: lead. Sample: paint.
b) Analyte: nitrate. Sample: soil.
c) Analyte: citric acid. Sample: Lime
1) Lead: Analyte.
2) Paint chips: Sample.
3) Soil: Sample.
4) Nitrate: Analyte.
5) Lime wedge: Sample.
6) Citric acid: Analyte.
Explanation:
A sample is a portion of material selected from a larger quantity of material while an analyte is the chemical of the system that will be analysed.
Thus:
a) Analyte is lead while you must take a sample of paint to analyze this lead.
b) Analyte is the nitrate while sample must be soil.
c) Analyte is citric acid and lime is the sample
1) Lead: Analyte.
2) Paint chips: Sample.
3) Soil: Sample.
4) Nitrate: Analyte.
5) Lime wedge: Sample.
6) Citric acid: Analyte.
Answer:
For 1 hour 75w light bulb requires 270 kj for burning
for 3 hours 75 w light bulb requires 270*3 = 810kj for burning
Explanation:
Explanation
Therefore
(b) The boiling point of AsH₃ from the boiling points of PH₃ (- 87.4°C) and SbH₃ (-17.1°C) (actual value = -55°C)
Answer:
a) Approximate boiling point of HBr = -60.15 °C
b) Approximate boiling point of AsH₃ = -52.25 °C
Explanation:
Döbereiner stated that some elements could be arranged in groups of 3 similar elements ( known as "triads) , and the element of the middle ( elements are ordered with respect to their atomic mass) would have properties between the other 2 ( the average value)
a) In the first case the triad would be the halogen triad ( Cl , Br and I ) . And according to Döbereiner , the boiling point of HBr should be the average of HCl and HI . Therefore
Approximate boiling point of HBr = [(- 84.9°C) + (-35.4°C)]/2 = -60.15 °C
b) Simmilarly for AsH₃ , PH₃ and SbH₃ , the boiling point of AsH₃ would be
Approximate boiling point of AsH₃ = [(- 87.4°C) + (-17.1°C)]/2 = -52.25 °C