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3 years ago

What is the boiling point of a solution of 12.0 g of urea in 165.0 g of water

Chemistry

1 answer:

Nat2105 [25]3 years ago

8 0

Answer:

T = 100.63 °C

Explanation:

To solve this question, we need to know what are we talking about here. In this case, we want to know the boiling point of a solution with Urea in water. This is a colligative property, so, the expression to use to calculate that is the following:

ΔT = m * K / MM * kg water (1)

Where:

ΔT: difference of temperatures (Tb of solution - Tb water)

m: mass of the urea

K: ebulloscopic constant of the water (0.52 ° C / m)

MM: molecular mass of urea

The boiling point of water is 100 °C, we have the mass of the urea, but not the molar mass. The urea has the formula CH₄N₂O, so the molar mass can be calculated using the atomic mass of the elements (I will use a rounded number for this):

MM = 12 + (4*1) + (2*14) + 16 = 60 g/mol

Now, we can calculate the ΔT and then, the boiling point of the solution:

ΔT = 12 * 0.52 / 60 * 0.165

ΔT = 6.24 / 9.9

ΔT = 0.63 °C

the value of ΔT is a difference between the boling point of water and the solution so:

ΔT = Ts - Tw

Ts = ΔT + Tw

Replacing we have:

Ts = 100 + 0.63

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2 years ago

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2 years ago

Select the correct set of quantum numbers (n, l, ml, ms) for the first electron removed in the formation of a cation for stronti

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Answer:

5,0,0,-1/2

Explanation:

The quantum numbers are a way to characterize the electrons, and so, identify the region that it's more probable to find it (orbital). They are:

- Principal quantum number (n): represents the shell or level, and varies from 1 to 7, and are represented by the letter K, L, M, N, O, P, and Q.

- Azimuthal quantum number (l): represents the subshell or sublevel, and is represented by 0,1,2,3.., and for the letters s, p, d, f,...

- Magnetic quantum number (ml): represents the orbital. It varies from -l to +l passing by 0. Each orbital can have 2 electrons.

- Spin quantum number (ms): represents the spin of the electron. It can be +1/2 or -1/2.

The strontium has an atomic number equal to 38, by the Linus Pauling's diagram, the electronic distribution is:

1s²2s²2p⁶3s²3p⁶4s²3d¹⁰4p⁶5s²

The valence electron is at the subshell 5s, which has only one magnetic quantum number: 0. Because it has 2 electrons, the first one has spin =1/2, and the other -1/2. So the first electron of the formation of cation has quantum numbers:

n = 5; l = 0; ml = 0; ms = -1/2

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2 years ago

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2 years ago

Does the reaction of a main-group metal oxide in water produce an acidic solution or a basic solution? Write a balanced equation

Fynjy0 [20]

<u>Answer:</u> The main group metal produce a basic solution in water and the reaction is $MO+H_2O\rightarrow M(OH)_2$

<u>Explanation:</u>

Main group elements are the elements that are present in s-block and p-block.

The metals that are the main group elements are located in Group IA, Group II A and Group III A.

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When a metal oxide is reacted with water, it leads to the formation of a base.

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The chemical equation for the reaction of metal oxide of Group II-A and water follows:

$MO+H_2O\rightarrow M(OH)_2$

Hence, the main group metal produce a basic solution in water and the reaction is $MO+H_2O\rightarrow M(OH)_2$

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2 years ago