Answer: Ice is melting due to the transfer of thermal energy from Jan's hand to ice.
Explanation: The melting of ice is a physical change and is happening when the thermal energy from Jan's hand is transferred to ice. Due to this energy transfer, the particles of ice starts to move faster and hence, making the ice melt.
In this, the physical state of ice is changing from solid to liquid state.
Norfenefrine (C₈H₁₁NO₂).
<h3>Further explanation</h3>We will solve a case related to one of the colligative properties, namely freezing point depression.
The freezing point of the solution is the temperature at which the solution begins to freeze. The difference between the freezing point of the solvent and the freezing point of the solution is called freezing point depression.
<u>Given:</u>
A mysterious white powder could be,
When 82 mg of the powder is dissolved in 1.50 mL of ethanol (density = 0.789 g/cm³, normal freezing point −114.6°C, Kf = 1.99°C/m), the freezing point is lowered to −115.5°C.
<u>Question: </u>What is the identity of the white powder?
<u>The Process:</u>
Let us identify the solute, the solvent, initial, and final temperatures.
Prepare masses of solutes and solvents.
We must prepare the solvent mass unit in kg because the unit of molality is the mole of the solute divided by the mass of the solvent in kg.
The molality formula is as follows:
Now we combine it with the formula of freezing point depression.
It is clear that we will determine the molar mass of the solute (denoted by Mr).
We enter all data into the formula.
We get
These results are very close to the molar mass of norfenefrine which is 153.18 g/mol. Thus the white powder is norfenefrine.
<h3>Learn more</h3>Keywords: a mysterious white powder, sugar, cocaine, codeine, norfenefrine, fructose, the solute, the solvent, dissolved, ethanol, normal freezing point, the freezing point depression, the identity
Answer:
293.15 K.
Explanation:
It is given that, the room temperature is 20 degrees Celsius.
We need to convert this temperature into kelvin.
The conversion from degrees Celsius to Kelvin is as follows :
We have,
So,
So, the room temperature is 293.15 kelvin.
Explanation:
It is known that in one day there are 24 hours. Hence, number of seconds in 24 hours are as follows.
Hence, total charge passed daily is calculated as follows.
And, number of Faraday of charge is as follows.
= 134300.52 F
The oxidation state of aluminium in is +3.
So, if we have to produce 1 mole of Al(s) we need 3 Faraday of charge.
Therefore, from 134300.52 F the moles of Al obtained with 89% efficiency is calculated as follows.
= 39842.487 mol
or, =
Molar mass of Al = 27 g/mol
Therefore, mass in gram will be calculated as follows.
Mass in grams =
=
= 1075.7 kg/day
Thus, we can conclude that the daily aluminum production of given aluminium is 1075.7 kg/day.
Answer:
c) 22
Explanation:
Let's consider the following balanced equation.
N₂(g) + 3 H₂(g) ----> 2 NH₃(l)
According to the balanced equation, 34.0 g of NH₃ are produced by 1 mol of N₂. For 170 g of NH₃:
According to the balanced equation, 34.0 g of NH₃ are produced by 3 moles of H₂. For 170 g of NH₃:
The total gaseous moles before the reaction were 5.00 mol + 15.0 mol = 20.0 mol.
We can calculate the pressure (P) using the ideal gas equation.
P.V = n.R.T
where
V is the volume (50.0 L)
n is the number of moles (20.0 mol)
R is the ideal gas constant (0.08206atm.L/mol.K)
T is the absolute temperature (400.0 + 273.15 = 673.2K)