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katen-ka-za [31]
3 years ago
13

Which of the following is kept constant when using a bomb calorimeter?

Chemistry
1 answer:
trapecia [35]3 years ago
6 0
Constant Volume Calorimetry, also know as bomb calorimetry, is used to measure the heat of a reaction while holding volume constant and resisting large amounts of pressure. Although these two aspects of bomb calorimetry make for accurate results, they also contribute to the difficulty of bomb calorimetry. In this module, the basic assembly of a bomb calorimeter will be addressed, as well as how bomb calorimetry relates to the heat of reaction and heat capacity and the calculations involved in regards to these two topics.

Introduction 

Calorimetry is used to measure quantities of heat, and can be used to determine the heat of a reaction through experiments. Usually a coffee-cup calorimeter is used since it is simpler than a bomb calorimeter, but to measure the heat evolved in a combustion reaction, constant volume or bomb calorimetry is ideal. A constant volume calorimeter is also more accurate than a coffee-cup calorimeter, but it is more difficult to use since it requires a well-built reaction container that is able to withstand large amounts of pressure changes that happen in many chemical reactions.

Most serious calorimetry carried out in research laboratories involves the determination of heats of combustion ΔHcombustion" role="presentation" style="display: inline-table; font-style: normal; font-weight: normal; line-height: normal; font-size: 14.4px; text-indent: 0px; text-align: left; text-transform: none; letter-spacing: normal; word-spacing: normal; word-wrap: normal; white-space: nowrap; float: none; direction: ltr; max-width: none; max-height: none; min-width: 0px; min-height: 0px; border: 0px; padding: 0px; margin: 0px; position: relative;">ΔHcombustionΔHcombustion, since these are essential to the determination of standard enthalpies of formation of the thousands of new compounds that are prepared and characterized each month. In a constant volume calorimeter, the system is sealed or isolated from its surroundings, and this accounts for why its volume is fixed and there is no volume-pressure work done. A bomb calorimeter structure consists of the following:

Steel bomb which contains the reactantsWater bath in which the bomb is submergedThermometerA motorized stirrerWire for ignition

is usually called a “bomb”, and the technique is known as bomb calorimetry

Another consequence of the constant-volume condition is that the heat released corresponds to qv , and thus to the internal energy change ΔUrather than to ΔH. The enthalpy change is calculated according to the formula

(1.1)ΔH=qv+ΔngRT" role="presentation" style="display: inline-table; font-style: normal; font-weight: normal; line-height: normal; font-size: 14.4px; text-indent: 0px; text-align: center; text-transform: none; letter-spacing: normal; word-spacing: normal; word-wrap: normal; white-space: nowrap; float: none; direction: ltr; max-width: none; max-height: none; min-width: 0px; min-height: 0px; border: 0px; padding: 0px; margin: 0px; width: 10000em !important; position: relative;">ΔH=qv+ΔngRT(1.1)(1.1)ΔH=qv+ΔngRT

Δng" role="presentation" style="display: inline-table; font-style: normal; font-weight: normal; line-height: normal; font-size: 14.4px; text-indent: 0px; text-align: left; text-transform: none; letter-spacing: normal; word-spacing: normal; word-wrap: normal; white-space: nowrap; float: none; direction: ltr; max-width: none; max-height: none; min-width: 0px; min-height: 0px; border: 0px; padding: 0px; margin: 0px; position: relative;">ΔngΔng  is the change in the number of moles of gases in the reaction.

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How manymoles of each ion are present in 175 mL of 0.147 M Fe2(SO4)3?
lilavasa [31]

Answer: 0.0257 moles of Fe^{3+}  and 0.0257 moles of SO_4^{2-}

Explanation:

Molarity of a solution is defined as the number of moles of solute dissolved per Liter of the solution.

Molarity=\frac{moles}{\text {Volume in L}}

moles of  Fe_2(SO_4)_3=Molarity\times {\text {Volume in L}}=0.147\times 0.175L=0.0257moles

The balanced reaction for dissociation will be:

Fe_2(SO_4)_3\rightarrow Fe^{3+}+SO_4^{2-}

According to stoichiometry:  

1 mole of Fe_2(SO_4)_3 gives 1 mole of Fe^{3+}  and 1 mole of SO_4^{2-}

Thus there will be 0.0257 moles of Fe^{3+}  and 0.0257 moles of SO_4^{2-}

8 0
3 years ago
A solution of KMnO4 has an absorbance of 0.539 when measured in the colorimeter. Determine the concentration of the KMnO4 given
loris [4]

Answer:

Concentration of unknown solution is 0.0416 M

Explanation:

As we know  

Absorbance is equal to the product of molar absorptivity of KMnO4 m, path length and concentration

From the given set of graphical data, it is clear that the absorbance vs concentration is a straight line.  

From the graph, we can obtain-  

Y = 5.73 X – 0.0065

Absorbance = 0.232

0.232 = 5.73 X – 0.0065

X = 0.0416  

Concentration of unknown solution is 0.0416 M

6 0
2 years ago
Rozwiaz logogryf. Z wyróżnionych pól odczytaj hasło i je zapisz.
saul85 [17]

Answer:

1) Nitrogen

2) Methane

3) Dipeptide

4) Ammonia

5) Glycine

In Polish/Po polsku

1) Azot

2) metan

3) dipeptyd

4) Amoniak

5) glicyna

Explanation:

English Translation

Solve logogriffs. Read the password from the highlighted fields and write it down.

1.The chemical element being the main component of air (it occupies 78% of its volume),

2. The simplest saturated hydrocarbon,

3. Is a result of combining two amino acid molecules,

4. Gas with a pungent odor, soluble in water; hydrogen and nitrogen synthesis product.

5. Common name of aminoacetic acid

(the first has four boxes, the second has five boxes, the third has eight quarters has seven, fifths and seven).

Thank you in advance

1) The main component of air that makes up 78% of the air is Nitrogen.

2) The simplest saturated hydrocarbon is the first member of the alkane family, Methane.

3) Two amino acids combine by forming peptide bonds between the carboxyl group of one amino acid and the amino group of another through dehydration synthesis (loss of 1 molecule of water). Hence, the result of the combination of two amino acids are called Dipeptides.

4) Nitrogen and Hydrogen come together to form only one known water soluble gas with pungent smell, called Ammonia.

5) Aminoacetic acid as its name suggests is an amino acid with the acetyl group. It is the simplest amino acid. The common name for this compound is Glycine.

In Polish/Po polsku

1) Głównym składnikiem powietrza, które stanowi 78% powietrza, jest azot.

2) Najprostszym nasyconym węglowodorem jest pierwszy członek rodziny alkanów, metan.

3) Dwa aminokwasy łączą się, tworząc wiązania peptydowe między grupą karboksylową jednego aminokwasu i grupą aminową innego przez syntezę odwodnienia (utrata 1 cząsteczki wody). Stąd wynik połączenia dwóch aminokwasów nazywa się dipeptydami.

4) Azot i wodór tworzą razem jeden znany gaz rozpuszczalny w wodzie o ostrym zapachu, zwany amoniakiem.

5) Kwas aminooctowy, jak sama nazwa wskazuje, jest aminokwasem z grupą acetylową. To najprostszy aminokwas. Powszechna nazwa tego związku to glicyna.

Hope this Helps!!!

Mam nadzieję że to pomoże!!!

8 0
3 years ago
Khalad is measuring the amplitude of a wave. What can be known about this wave?
lorasvet [3.4K]
B.It is a transverse wave
6 0
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Read 2 more answers
1. Describe the process of gene splicing.
AnnyKZ [126]

Answer:

The DNA is cut using special chemicals called restriction enzymes,.

DNA ligase are used to insert genes and other pieces of DNA into plasmids.

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