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3 years ago

PLEASE HELP! MAJOR GRADE!

Chemistry

1 answer:

chubhunter [2.5K]3 years ago

5 0

Answer:

A, B, and C are the correct answers.

Explanation:

The reason why solid, liquid, and gas are the most common of the elements because usually in school they teach you more about those 3 elements more than plasma ( from where I am ). Also, all of these states behave differently. Liquid is a substance that flows freely but is of constant volume, having a consistency like that of water or oil. Solid is firm and stable in shape. And gas is an air like substance. I'm not sure how to explain this more, it sounded better in my head. Hope this helped though!

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Please calculate the mixed volume (Vmix) when 0.300 mol of ethanol and 0.200 mol of water are mixed. Hint: The partial molar vol

Grace [21]

Answer:

If we assume the molar volumes of water and ethanol 17.0 and 57.0 cm³/mol, respectively, Vmix = 20.5 cm³.

Explanation:

The molar volume of a substance is the ratio between the volume and the number of moles of the substance. It represents the volume that 1 mol of it occupies. Because we don't have access to page 24, let's assume the molar volumes of water and ethanol 17.0 and 57.0 cm³/mol, respectively.

The volume of mixture (Vmix) is the sum of the volume of each substance, which is the number of moles multiplied by molar volume, so:

Vmix = 0.300*57 + 0.200*17

Vmix = 17.1 + 3.4

Vmix = 20.5 cm³

7 0

3 years ago

At 7 degrees Celsius the volume of gas is 49 liters. At the same pressure its volume is 74 mL at what temperature

Romashka-Z-Leto [24]

Charle's law gives the relationship between volume and temperature of gas.
It states that at constant pressure, volume of gas is directly proportional to temperature of gas.
V/T = k
where V - volume , T - temperature and k- constant
$\frac{V1}{T1} = \frac{V2}{T2}$
parameters for the first instance are on the left side of the equation and parameters for the second instance are on the right side of the equation
T1 - 7 °C + 273 = 280 K
substituting these values in the equation
$\frac{49 mL}{280K} = \frac{74 mL}{T}$
T = 423 K
temperature in Celcius scale - 423 K - 273 = 150 °C

4 0

4 years ago

Oxygen gas can be prepared by heating potassium chlorate according to the following equation: 2KClO3(s)2KCl(s) + 3O2(g) The prod

Ipatiy [6.2K]

Answer:

The number of moles of KClO₃ reacted was 0,15 mol

Explanation:

For the reaction:

2KClO₃(s) → 2KCl(s) + 2O₂(g)

The only gas product is O₂.

Total pressure is the sum of vapor pressure of water with O₂ gas formed. Thus, pressure of O₂ is:

749mmHg - 23,8mmHg = 725,2mmHg

Using gas law:

PV/RT = n

Where:

P is pressure (725,2mmHg ≡ 0,9542atm)

V is volume (5,76L)

R is gas constant (0,082 atmL/molK)

And T is temperature (25°C ≡ 298,15K)

Replacing, number of moles of O₂ are 0,2248 moles

As 2 moles of KClO₃ react with 3 moles of O₂ the moles of KClO₃ that reacted was:

0,2248 mol O₂× $\frac{2 mol KClO_{3}}{3 mol O_{2}}$ = 0,15 mol of KClO₃

I hope it helps!

8 0

4 years ago

What is the pH of a 0.640 M solution of C₅H₅NHBr (Kb of C₅H₅N is 1.7 × 10⁻⁹)?

Elden [556K]

The pH of a 0.64 M solution of pyridine (C₅H₅N) is 9.52.

A figure expressing the acidity or alkalinity of a solution on a logarithmic scale on which 7 is neutral, lower values are more acid and higher values more alkaline.

The equation for the protonation of the base pyridine is the following:

C₅H₅N + H₂O ⇄ C₅H₅NH⁺ + OH⁻ (1)

Kb = 1.7 × 10⁻⁹ (Given)

To calculate the pH of the solution we need to use the following equation:

pH + pOH = 14

pH = 14 - pOH

=14 - [-log[OH⁻]]

= 14 + log[OH⁻]

Now, we need to find the concentration of the OH⁻ ions. Since pyridine is a weak base, at the equilibrium we have (eq 1):

C₅H₅N + H₂O ⇄ C₅H₅NH⁺ + OH⁻

0.64 - x x x

After entering the values of [C₅H₅N] = 0.64-x, [C₅H₅NH⁺] = x, and [OH⁻] = x, into equation (2) we can find the concentration of OH⁻:

1.7 × 10⁻⁹ =[C₅H₅NH⁺] [OH⁻] / [C₅H₅N]

= x . x / 0.64-x

1.7 × 10⁻⁹ (0.64-x) - x² = 0

Solving the above quadratic equation for x, we have :

x₁ = -3.32 x 10⁻⁵
x₂ = 3.32 x 10⁻⁵

Now, We can calculate the pH, after taking the positive value, x₂, (concentrations cannot be negative) and entering into above equation :

pH = 14 + log[OH⁻]

= 14 + log (3.32 x 10⁻⁵)

= 9.52

Therefore, the pH of the solution of pyridine is 9.52.

Find more about pH here:

brainly.com/question/8834103?referrer=searchResults

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3 0

2 years ago

Which formula can be used to calculate the theoretical yield?

Bas_tet [7]

Answer:

Option C, (Actual yield ÷ percent yield) × 100

Explanation:

Theoretical yield is defined as the total amount of product formed for given reactants in a chemical reaction. It is an ideal case which assumes no exceptions or wastage.

The mathematical relation between the actual yield, percent yield and theoretical yield is as follows -

$P.Y. = \frac{M_{A.Y.}}{M_{T.Y.}} * 100$

Where

P.Y. represents the percent yield a

M A.Y. represents the mass obtained from actual yield

M T.Y. represents the mass obtained from theoretical yield

Hence, if we rearrange the formula, we get -

$M_{T.Y.} = \frac{M_{A.Y.}}{P.Y.} * 100$

Hence, option C is correct

5 0

3 years ago