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My name is Ann [436]
3 years ago
14

According to the cooling curve, what is the approximate freezing point of the substance?

Chemistry
2 answers:
Dmitry_Shevchenko [17]3 years ago
6 0

Correct answer: B

Cooling curve is the plot of temperature versus time as the sample is allowed to cool. In a cooling curve, we start at a temperature greater than the boiling point. At this temperature, the sample is in gaseous state. At the boiling point, there is no change in temperature as the gaseous and liquid states are in equilibrium. As the temperature reduces further, the liquid starts to condense and at the melting point of the sample the liquid undergoes phase transition to solid state. At the melting temperature, a second plateau is observed as the temperature remains unchanged. At temperatures below the melting point, the sample exists as a solid.

So from the curve, the second plateau is observed at around -111^{0}C. This point represents the phase transition from liquid to solid state.

Vilka [71]3 years ago
5 0

Answer:

Its B broooooooo

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Aluminum reacts with sulfur gas to produce aluminum sulfide. a) What is the limiting reactant? What is the excess reagent? b) Ho
Sophie [7]

Answer:

a) Limiting: sulfur. Excess: aluminium.

b) 1.56g Al₂S₃.

c) 0.72g Al

Explanation:

Hello,

In this case, the initial mass of both aluminium and sulfur are missing, therefore, one could assume they are 1.00 g for each one. Thus, by considering the undergoing chemical reaction turns out:

2Al(s)+3S_2(g)\rightarrow 2Al_2S_3(s)\\

a) Thus, considering the assumed mass (which could be changed based on the one you are given), the limiting reagent is identified as shown below:

n_S^{available}=1.00gS_2*\frac{1molS_2}{64gS_2} =0.0156molS_2\\n_S^{consumed\ by \ Al}=1.00gAl*\frac{1molAl}{27gAl}*\frac{3molS_2}{2molAl}=0.0556molS_2

Thereby, since there 1.00g of aluminium will consume 0.0554 mol of sulfur but there are just 0.0156 mol available, the limiting reagent is sulfur and the excess reagent is aluminium.

b) By stoichiometry, the produced grams of aluminium sulfide are:

m_{Al_2S_3}=0.0156molS_2*\frac{2molAl_2S_3}{3molS_2} *\frac{150gAl_2S_3}{1molAl_2S_3} =1.56gAl_2S_3

c) The leftover is computed as follows:

m_{Al}^{excess}=(0.0556-0.0156)molS_2*\frac{2molAl}{3molS_2}*\frac{27gAl}{1molAl} =0.72 gAl\\

NOTE: Remember I assumed the quantities, they could change based on those you are given, so the results might be different, but the procedure is quite the same.

Best regards.

7 0
3 years ago
How many mL will a 0.205 mole sample of He occupy at 3.00 atm and 200 K? Report your answer to the nearest mL.
Tcecarenko [31]

1.1214 mL will a 0.205-mole sample of He occupy at 3.00 atm and 200 K.

<h3>What is an ideal gas equation?</h3>

The ideal gas law (PV = nRT) relates the macroscopic properties of ideal gases. An ideal gas is a gas in which the particles (a) do not attract or repel one another and (b) take up no space (have no volume).

Using equation PV=nRT, where n is the moles and R is the gas constant. Then divide the given mass by the number of moles to get molar mass.

Given data:

P= 3.00 atm

V= ?

n=0.205 mole

R= 0.082057338 \;L \;atm \;K^{-1}mol^{-1}

T=200 K

Putting value in the given equation:

\frac{nRT}{P} =V

V= \frac{0.205 \;mole\;0.082057338 \;L \;atm \;K^{-1}mol^{-1} X 200}{3 \;atm}

V= 1.1214 mL

Learn more about the ideal gas here:

brainly.com/question/27691721

#SPJ1

4 0
1 year ago
Which statement describes a system that consists of sugar crystals dissolving in water?
trapecia [35]

To know the answer, you either know what is really the nature and chemistry of a sugar solution. You can also know the answer by knowing the meaning of entropy. Entropy is often interpreted as the degree of disorder or randomness in the system. So the correct statement is that the system becomes more disordered and has an increase in entropy.

7 0
3 years ago
Read 2 more answers
What the atmosphere mean
Alex_Xolod [135]
The envelope of gases surrounding the earth or another planet.
3 0
3 years ago
Calculate the standard entropy change for the following reaction cu(s) + 1/2 O2(g) —&gt; cuo(s)
Evgen [1.6K]

3433Explanation:

the awser sucks and its not RIGHT

8 0
2 years ago
Read 2 more answers
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