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2 years ago

A cube with a mass of 250.0 g has sides measuring 5.00 cm each. What is the density of this cube in grams per cubic centimeter?

Chemistry

1 answer:

stiks02 [169]2 years ago

5 0

The density of the cube in grams per cubic centimeter = D = 2 gram / cm³

Explanation:

The Volume Of the Cube is V = a³

Its is given that the cube has sides measuring 5 cm each side.

V = ( 5 )³

= 5cm 5cm 5cm

V = 125 cm³

The Density Formula, Density= Mass / Volume.

Given that this cube has a mass of 250 grams.

to calculate density

D = ρ = m / V

= 250 / 125

= 2

D = 2 gram / cm³

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A sample of pure NO2 is heated to 337?C at which temperature it partially dissociates according to the equation2NO2(g)?2NO(g)+O2

tatyana61 [14]

Answer: Kc =5.915. $10^{-3}$

Explanation: Kc is an equilibrium constant of a chemical reaction and is dependent upon the reagents and products concentration. For this reaction, Kc is: Kc = $\frac{[NO]^{2} .[O2]}{[NO2]^{2} }$

To determine each concentration, we have to find each relation:

From the reaction, we know that [NO] = 2[O2] (1)

From the Ideal Gas Law,

P·V=ntotal·R·T

$\frac{P}{RT}=\frac{ntotal}{V}$

$\frac{P}{RT} = \frac{n(NO2)}{V} + \frac{n(NO)}{V} + \frac{n(O2)}{V}$

[NO2]+{NO}+[O2] = $\frac{0.745}{0.082.610}$ = 0.015 mol/L

As [NO] = 2[O2]

[NO2]+2[O2]+[O2]=0.015

[NO2] = 0.015 - 3[O2] (2)

To resolve this equation, we will turn towards density of the mixture:

ρ = $\frac{m(NO2)+m(NO)+m(O2)}{V}$

Substituting mass for molar mass and number of molar,

ρ = M(NO2)· $\frac{n(NO2)}{V}$ +M(NO)· $\frac{n(NO)}{V}$ +M(O2)· $\frac{n(O2)}{V}$

Knowing the molar mass of each molecule:

ρ = 46·[NO2]+30·[NO]+32·[O2] = 0.525 g/L (3)

Substituting (1), (2) and (3) we have:

46(0.015 - 3[O2])+30(2[O2])+32.[O2]=0.525

32[O2]+60[O2]-138[O2]=0.0525-0.69

-48[O2]= -0.6375

[O2]=13.3. $10^{-3}$ M

Calculating for [NO]

[NO]=2[O2]

[NO]=2.13.3. $10^{-3}$

[NO]=26.6. $10^{-3}$ M

And finding [NO2],

[NO2]=0.015 - 3[O2]

[NO2]=0.015 - 3.13.3. $10^{-3}$

[NO2]=39.885. $10^{-3}$ M

So, to calculate Kc:

Kc = (26.6. $10^{-3}$ )²· 13.3. $10^{-3}$ / (39.885. $10^{-3}$ )²

Kc= 5.915. $10^{-3}$

The Kc is 5.915. $10^{-3}$ .

6 0

2 years ago

A paint machine dispenses dye into paint cans to create different shades of paint. The amount of dye dispensed into a can is kno

frosja888 [35]

Answer:

The 9th percentile is 4.464ml

Explanation:

Hello!

Given the variable X: Amount of dye dispensed into a paint can.

With a normal distribution, mean μ= 5ml and standard deviation δ= 0.4ml

You need to calculate the 9th percentile of the distribution.

The percentile is a measure of the position that indicates the number that separates the distribution or data set in a percentage of interest. In this case, the 9th percentile is the value of the distribution that separates the bottom 9% from the top 91%.

Symbolically:

P(X≤x₀)= 0.09

x₀ represents the value of the percentile.

The best way to calculate this value is by using the standard normal distribution since it is already tabulated, and then "translate" the Z-value to a value of the variable.

Under the standard normal distribution you have to look for:

P(Z≤z₀)= 0.09

The value marks the bottom 9% of the distribution, this means that you'll find it in the left tail of it. Remember the mean of the standard normal distribution is zero, so all values under the mean will be negative. Using the left entry of the Z-table you have to look for 0.09 in the body of the table and reach the margins to find the corresponding value:

z₀= -1.34

Now using the formula of the distribution you can "translate" the Z-value in terms of the variable of interest

Z=(X-μ)/ δ ~N(0;1)

z₀=(x₀-μ)/ δ

z₀*δ=x₀-μ

x₀=(z₀*δ)+μ

x₀=(-1.34*0.4)+5

x₀= 4.464

The 9th percentile is 4.464ml

I hope you have a SUPER day!

4 0

2 years ago

Tear gas has the composition 40.25% carbon, 6.19% hydrogen, 8.94% oxygen, 44.62% bromine. what is the empirical formula of this

andre [41]

Calculating the moles and the moles ratio of the elements gives us the ratio of atoms in each element. Converting the percentage of element into grams 40.25% carbon = 40.25/100 = .4025 * 100 g of carbon = 40.25g of C 6.19% hydrogen = 6.19/100 = .0619 * 100g g of hydrogen = 6.19g of H 8.94% oxygen = 8.94/100 = .0819 * 100 g of oxygen = 8.19g of O 44.62% bromine = 44.62/100 = .4462 * 100 g of bromine = 44.62g of Br Converting the grams of element into moles (48.38 g C) (1 mol/ 12.10 g C) = 4.028 mol C (8.12 g H) (1 mol/ 1.008 g H) = 8.056 mol H (53.38 g O) (1 mol/ 16.00 g O) = 3.336 mol O (44.62g of Br)(0.012515018021626 moles) = 0.55842 mol Br Calculating the moles ratio of elements by dividing the small number of moles of an element 4.028 mol C /0.55842 = 7.2 mol C x 5 = 36 mol C 8.056 mol H / 0.55842 = 14.42 mol H = 72 mol H 3.336 mol O / 0.55842 = 5.97 mol O = 30 mol O 0.55842 mol Br / 0.55842 = 1mol Br = 5 mol Br So the empirical formula is (C6H12O5)6Br5

8 0

2 years ago

Read 2 more answers

A mixture of three gases has a pressure at 298 K of 1380 mm Hg. The mixture is analysed and is found to contain 1.27 mol CO2, 3.

enot [183]

Answer:

The partial pressure of Ar is 356.04 mm Hg (= 0.4685 atm)

Explanation:

Step 1: Data given

A mixture of three gases has a total pressure of 1380 mm Hg (=1.81579 atm) at 298 K

Moles of CO2 = 1.27 moles

Moles of CO = 3.04 moles

Moles of Ar = 1.50 moles

Step 2: Calculate total number of moles

Total number of moles = n(CO2)+ n(CO)+ n(Ar) = 1.27 mol+ 3.04 mol+ 1.50 mol = 5.81 moles

Step 3: Calculate mol fraction Ar

Mol fraction Ar = 1.50 mol/5.81 mol = 0.258

Step 4: Calculate partial pressure

1380 mm Hg * 0.258 moles Ar = 356.04 mm Hg = 0.4685 atm

The partial pressure of Ar is 356.04 mm Hg (= 0.4685 atm)

8 0

2 years ago

Which of these tasks falls under the responsibility of a forensic scientist?

Varvara68 [4.7K]

Answer:

Training officers in how to properly collect evidence

Explanation:

Forensic science is an interesting branch of science that involves the use of scientific procedures to solve a crime case. It encompasses collection of physical evidence from the crime scene and analyzing it in a laboratory using scientific means.

A forensic scientist is the individual in charge of performing these scientific procedures. His/her major role is to run the scientific analysis of the physical evidence brought in by the officers, however, he/she can also perform the task of training officers in how to properly collect evidence, in order not to damage the evidence or render it invalid for use.

8 0

2 years ago