6) Which type of orbital is represented by this image?"<br> Z,Y,X

A 0.500-g sample of KCl is added to 50.0g of water in a calprimeter (Figure 5.12) If the temperature decreases by 1.05C. what is

Sauron [17]

Answer : The reaction is endothermic.

Explanation :

Formula used :

$Q=m\times c\times \Delta T$

where,

$\Delta T$ = change in temperature = $1.05^oC$

Q = heat involved in the dissolution of KCl = ?

m = mass = 0.500 + 50.0 = 50.5 g

c = specific heat of resulting solution = $4.18J/g^oC$

Now put all the given value in the above formula, we get:

$Q=50.5g\times 4.18J/g^oC\times 1.05^oC$

$Q=+221.64J$

The heat involved in the dissolution of KCl is positive that means as the change in temperature decreases then the reaction is endothermic and as the change in temperature increases then the reaction is exothermic.

Hence, the reaction is endothermic.

8 0

3 years ago

Why do you use the same amount of water for each shape of ice?

Fiesta28 [93]

Answer:

Ice is a solid form of liquid. Water simply expands when it freezes.

The same amount of water for each shape of ice because the melting rate of ice depends on the surface area of each shape. So the same amount of water or volume with a large surface area will remain frozen for longer time.

4 0

3 years ago

A mysterious white powder could be powdered sugar (C12H22O11), cocaine (C17H21NO4), codeine (C18H21NO3), norfenefrine (C8H11NO2)

rodikova [14]

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.

$\boxed{ \ \Delta T_f = T_f(solvent) - T_f(solution) \ } \rightarrow \boxed{ \ \Delta T_f = K_f \times molality \ }$

<u>Given:</u>

A mysterious white powder could be,

powdered sugar (C₁₂H₂₂O₁₁) with a molar mass of 342.30 g/moles,
cocaine (C₁₇H₂₁NO₄) with a molar mass of 303.35 g/moles,
codeine (C₁₈H₂₁NO₃) with a molar mass of 299.36 g/moles,
norfenefrine (C₈H₁₁NO₂) with a molar mass of 153.18 g/moles, or
fructose (C₆H₁₂O₆) with a molar mass of 180.16 g/moles.

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.

The solute = the powder
The solvent = ethanol
The freezing point of the solvent = −114.6°C
The freezing point of the solution = −115.5°C

Prepare masses of solutes and solvents.

Mass of solute = 82 mg = 0.082 g
Mass of solvent = density x volume, i.e., $\boxed{ \ 0.789 \ \frac{g}{cm^3} \times 1.50 \ cm^3 = 1.1835 \ g = 0.00118 \ kg \ }$

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:

$\boxed{ \ m = \frac{moles \ of \ solute}{kg \ of \ solvent} \ } \rightarrow \boxed{ \ m = \frac{mass \ of \ solute \ (g)}{molar \ mass \ of \ solute \times kg \ of \ solvent} \ }$

Now we combine it with the formula of freezing point depression.

$\boxed{ \ \Delta T_f = K_f \times \frac{mass \ of \ solute \ (g)}{molar \ mass \ of \ solute \times kg \ of \ solvent} \ }$

It is clear that we will determine the molar mass of the solute (denoted by Mr).

We enter all data into the formula.

$\boxed{ \ -114.6^0C - (-115.5^0C) = 1.99 \frac{^0C}{m} \times \frac{0.082 \ g}{Mr \times 0.00118 \ kg} \ }$

$\boxed{ \ 0.9 = \frac{1.99 \times 0.082}{Mr \times 0.00118} \ }$

$\boxed{ \ Mr = \frac{0.16318}{0.9 \times 0.00118} \ }$

We get $\boxed{ \ Mr = 153.65 \ }$

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>

The molality and mole fraction of water brainly.com/question/10861444
About the mass and density of ethylene glycol as an antifreeze brainly.com/question/4053884
About the solution as a homogeneous mixture brainly.com/question/637791

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

7 0

3 years ago

Read 2 more answers

Identify the element: 6 energy level, metallic, 82 election

Lady bird [3.3K]

<u>Answer</u>:-

Name of element = Lead

Symbol ♾ of Lead = Pb

Atomic no. = 82

Atomic mass = 207.2 amu

No. of protons = 82

No. of electrons = 82

Yes, lead(Pb) is a metallic element and certainly it has 6 electron shells which means 6 energy level.

If you find anything unclear you can ask me...

6 0

3 years ago

The chemical formula for glucose (sugar) is C6H12O6. What are the individual numbers called in a chemical formula?

givi [52]

The individual numbers which are present in chemical formula is subscript.

<h3>What is chemical formula?</h3>

Chemical formula of any compound of chemistry consist more than one atoms in it and gives idea about the number of atoms present in that compound.

Given chemical formula of glucose is C₆H₁₂O₆.

In the given chemical formula of glucose, number which shows the amount of carbon, hydrogen and oxygen are known as subscripts.

Hence, individual number are subscript.

To know more about chemical formula, visit the below link:
brainly.com/question/1603500

#SPJ1

8 0

2 years ago

6) Which type of orbital is represented by this image?" Z,Y,X