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2 years ago

Which one of these statements about carbon tetrachloride fire extinguishers is true?

Chemistry

1 answer:

Fofino [41]2 years ago

5 0

Answer;

-Prohibited from use by OSHA

Explanation;

-Carbon tetrachloride is a clear and colorless liquid with an odor similar to that of chloroform.It is employed as a chemical reagent for a number of purposes, as a raw material in chemical manufacture and is, used very widely as a reagent to extinguish fires.

-It volatizes very easily, is a non-conductor of electricity and, as noted above, freezes at very low temperatures.

-It is effective, due to the blanketing effect of its vaporized fumes, on many Class B or volatile, flammable liquid fires and because it will mix with certain volatile, flammable liquids and form a non-burning combination.

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Mass is usually measured using ?

Brut [27]

Balance
Usually it’s a triple beam balance.
A ruler measures length

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2 years ago

A closed, frictionless piston-cylinder contains a gas mixture with the following composition on a mass basis: 40% carbon dioxide

Hitman42 [59]

Answer:

W=-37.6kJ, therefore, work is done on the system.

Explanation:

Hello,

In this case, the first step is to compute the moles of each gas present in the given mixture, by using the total mixture weight the mass compositions and their molar masses:

$n_{CO_2}=0.8kg*0.4*\frac{1kmolCO_2}{44kgCO_2}= 0.00727kmolCO_2\\\\n_{O_2}=0.8kg*0.25*\frac{1kmolO_2}{32kgO_2}=0.00625kmolO_2\\ \\n_{Ne}=0.8kg*0.35*\frac{1kmolNe}{20.2kgNe}=0.0139kmolNe$

Next, the total moles:

$n_T=0.00727kmol+0.00625kmol+0.0139kmol=0.02742kmol$

After that, since the process is isobaric, we can compute the work as:

$W=P(V_2-V_1)$

Therefore, we need to compute both the initial and final volumes which are at 260 °C and 95 °C respectively for the same moles and pressure (isobaric closed system)

$V_1=\frac{n_TRT_1}{P}= \frac{0.02742kmol*8.314\frac{kPa*m^3}{kmol\times K}*(260+273)K}{450kPa}=0.27m^3\\ \\V_2=\frac{n_TRT_2}{P}= \frac{0.02742kmol*8.314\frac{kPa*m^3}{kmol\times K}*(95+273)K}{450kPa}=0.19m^3$

Thereby, the magnitude and direction of work turn out:

$W=450kPa(0.19m^3-0.27m^3)\\\\W=-37.6kJ$

Thus, we conclude that since it is negative, work is done on the system (first law of thermodynamics).

Regards.

7 0

2 years ago

Are people made up of matter? Do they have mass?

GaryK [48]

Yes. Everything is made up of mass. If it takes up space, it has mass

3 0

2 years ago

If 3 moles of a compound use 12 J of energy in a reaction, what is the Hreaction in kJ/mol

igomit [66]

Answer:

$\Delta _RH=4x10^{-3}\frac{kJ}{mol}$

Explanation:

Hello,

In this case, the molar enthalpy of reaction is obtained by dividing the involved energy by the reacting moles:

$\Delta _RH=\frac{12J}{3mol} =4\frac{J}{mol}$

Thus, it is important to notice that the compound "uses" the energy, it means that it absorbs the energy, for that reason the sign is positive. Moreover, computing the result in kJ/mol we finally obtain:

$\Delta _RH=4\frac{J}{mol}*\frac{1kJ}{1000J} =4x10^{-3}\frac{kJ}{mol}$

Best regards.

5 0

2 years ago

Lithium iodide has a lattice energy of −7.3×102kJ/mol and a heat of hydration of −793kJ/mol. Find the heat of solution for lithi

Anna007 [38]

Delta H of solution = -Lattice Energy + Hydration
Delta H of solution=- (-730)+(-793) 
Delta H of solution= -63kJ/mol 

Now we find moles of LiI: 
10gLiI/133.85g=.075moles 
multiply moles to the delta H of solution to cross cancel moles. .75moles x -64kJ/mol =4.7

7 0

2 years ago

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