Helium occupies a volume of 3.8 L at –45°C. What was its initial temperature when it occupied 8.3 L?

Answer:

[tex]pOH=1.3[/tex]

Explanation:

Hello,

In this case, since pH is computed by knowing the concentration of hydrogen ions, one could compute the pOH by knowing the concentration of the hydroxyl ions as in this case which is 0.045M as shown below:

[tex]pOH=-log([OH^-])=-log([0.045])\\\\pOH=1.3[/tex]

Best regards.

Answer:

The pOH of the 0.045 M solution is 1.3

The second option (1.3) is correct

Explanation:

Step 1: Data given

Concentration [OH-] of KOH is 0.045 M

Step 2: Calculate pOH

pOH = -log[OH-]

pOH = -log (0.045)

pOH = 1.3

The answer:

The pOH of the 0.045 M solution is 1.3

The second option (1.3) is correct

Answer:

Sulfur Trioxide

Explanation:

Sulfur trioxide is a gas that reacts with liquid water to produce aqueous sulfuric acid,or acid rain.

Answer:

81.54 °C

Explanation:

Use the equation

q = mcΔT

348 = 20.9(0.902)(100-t)

t = 81.54 °C

*note, you don't have to convert these to kelvin since the difference will be the same

Answer:

1.52M in NaCl

Explanation:

Molarity = moles solute / volume solution in Liters

=> molarity (M) = 3.8 moles / 2.5 Liters solution = 1.52 molar solution in NaCl

Answer: 1.52

Explanation:

Answer:

The porosities in dental materials can be of merit and not merit since some dental materials need to be porous in order to reduce their weight and improve their properties and functions, whereas in those (which are the majority) porosities are not Merit, see the properties of the material, the function and can even influence dental rehabilitation.

An example of this is the use of vitreous ionomers, which is a dental material, where when it is spatulated it remains porous, it can give recurrence of infectious caries, since its permeability increases, the best cariogenic microorganisms are filtered and porosity works as a retentive site for these microorganisms that make up the dental biofilm.

In summary, the world of dental materials is very wide, some are resins, other cements, others have metallic claims, etc. To say that the presence of porosity is merit or demerit would be ideal because for some materials this is favorable and for others unfavorable since they are very versatile, with different qualities, different degrees of porosity, different molecules, different coefficients of thermal expansion, some do not set, others do not, some are light-cured, others do not, some withstand more mechanical forces and have more elastic modulus and less porosity, while others do not, and thus with many more variables.

Explanation:

In the manufacture of dental materials, much attention is always paid to what the manufacturer indicates in these indications that come on the reverse side of the material or on a paper inside the material container.

This is important to know, because the manufacturer is the one that indicates the mode of use and working time according to the trademark and the chemical composition of the dental material.

That a dental material in its manufacture is more or less porous, makes its density, weight and volume possibly be affected, there are materials that seek to increase porosity for a certain purpose, while others seek the opposite, depending on the function that is applied, will have more or less pores.

The example we gave above about the vitreous ionomer is an example that indicates that in the case of restorative dental materials where the function is to SEAL the porosity is almost nil, since otherwise it will not seal the cavity that was formed with caries and not the infectious problem would be solved.

On the other hand, in the surgical field of dentistry there are bone grafts or porous macroparticles that are for the purpose of bone replacement, which in order to be integrated need blood vessels that run over these pores, irrigating the area of ​​bone neoformation well, in this case the merit of porosity if necessary and it is essential that they be very porous.

Answer:

PCl3 or option C

Explanation:

For everyone taking edge, trust me. Most of the answers are half-fasted, and offer no explanation. My explanation is that this is the right answer and you can trust me. Im taking the courses just like all of you, so i have no reason to misslead. Hope this helps! if you require more information, i cannot offer it. I gain knowledge by my failures.

Answer:

The correct answer is 250. kJ

Also referred to as C or Option 3

Explanation:

I got the answer correct because of the help from the other answer. Therefore, please mark the other person brainliest, they deserve it!

Answer:

17202.6 years

Explanation:

Activity of the living sample (Ao) = 160 counts per minute

Activity of the wood sample (A) = 20 counts per minute

Half life of carbon-14 = 5730 years

t= age of the artifact

From;

0.693/t1/2= 2.303/t log Ao/A

Then;

0.693/ 5730= 2.303/t log Ao/A

Substituting values;

0.693/5730= 2.303/t log (160/20)

Then we obtain;

1.209×10^-4 = 2.0798/t

t= 2.0798/1.209×10^-4

Thus;

t= 17202.6 years

Therefore the artifact is 17202.6 years old.

Answer:

a)

[H₂O] = 0.0455M

[Cl₂O] = 0.0130M

[HOCl] = 0.0200M

b) Kc = 0.676

c) [H₂O] = [Cl₂O] = 0.177M

Explanation:

Based on the reaction:

H₂O(g) + Cl₂O(g) ⇄ 2HOCl(g)

Kc is defined as:

Kc = [HOCl]² / [H₂O][Cl₂O] For molar concentrations in equilibrium

As volume of the flask is 1.00L, the initial molar concentrations of H₂O and Cl₂O is 0.0555M and 0.0230M, respectively.

In equilibrium, the concentrations are:

[H₂O] = 0.0555M - X

[Cl₂O] = 0.0230M - X

[HOCl] = 2x = 0.0200M → X = 0.0100M

Where X is reaction coordinate

a) Concentrations in equilibrium are:

[H₂O] = 0.0455M

[Cl₂O] = 0.0130M

[HOCl] = 0.0200M

b) Replacing in Kc:

Kc = [0.0200]² / [0.0455][0.0130] = 0.676

c) Initial concentration of HOCl is 1.0mol / 2.0L = 0.50M. In equilibrium concentrations are:

[H₂O] = X

[Cl₂O] = X

[HOCl] = 0.50M - 2X

Replacing in Kc formula:

0.676 = [0.50-2X]² / [X][X]

0.676X² = 4X² - 2X + 0.25

0 = 3.324X² - 2X + 0.25

Solving for X:

X = 0.177M

X = 0.425M → False answer, produce negative concentrations.

As X = [H₂O] = [Cl₂O]; equilibrium concentrations of both compounds is 0.177M

Answer:

[tex]pH=10.5[/tex]

Explanation:

Hello,

In this case, since we define the pH as:

[tex]pH=-log([H^+])[/tex]

We can directly compute it by using the given concentration of H⁺:

[tex]pH=-log(3.5x10^{-11})\\\\pH=10.5[/tex]

For which we conclude it is a basic solution as the pH is greater than 7.

Best regards.

Answer:

[tex]P_2=50kPa[/tex]

Explanation:

Hello,

In this case, we can apply the Boyle's law in order to understand the pressure-volume relationship as an inversely proportional relationship relating the initial and the final volume:

[tex]P_1V_1=P_2V_2[/tex]

Next, we compute the final pressure P2:

[tex]P_2=\frac{P_1V_1}{V_2}=\frac{100.00kPa*500.0mL}{1000.0mL} \\\\P_2=50kPa[/tex]

Thus we validate, the higher the volume the lower the pressure.

Best regards.

Answer:

being stationary relative to a particular frame of reference or another object; when the position of a body with respect to its surroundings does not change with time it is said to be at rest

Explanation:

Been stationary is the normal resting position of an object

When an object is at rest ( normal resting position ) it is stationary ( i.e. the position of the object does not change with time in relation to its environment or another object/reference  )

When an object is at rest it posses its' highest potential energy and its least kinetic energy. therefore been stationary is the normal resting position of an object.

Hence we can conclude that Been stationary is the normal resting position of an object.

Learn more : https://brainly.com/question/22533065

Answer:

made regular payments to the emperor.

Explanation:

The Aztec Empire was an alliance of three states: Mexico-Tenochtitlan, Texcoco, and Tlacopan. The area in and around the Valley of Mexico was ruled by these three city-states from 1428 to 1521. The state religion of the empire was polytheistic. The tribute states of the ancient Aztec empire made regular payments to the emperor.

Answer:

B

Explanation:

Answer:

Physical change

Explanation:

Because it doesn't require any chemical to change

Answer:

Physical change

Physical change

Physical change

Physical change

Explanation:

Answer:

The correct answer is 7.8 percent.

Explanation:

As mentioned in the given question, the absorbance (A) of the sample solution is 1.07. To find the concentration of aspirin, Beer's law is used, that is, A = ebc

Here, e is the extinction coefficient, which is equal to 139.322 M^-1cm^-1 as per the standard value for salicylic acid, b is the pathlength, which is equivalent to 1 cm. Now putting the values we get,  

A = ebc

c = A / (eb)

c = 1.07 / (139.322 × 1)

c = 0.00768 M

Now to determine the percent salicylic acid in the sample, there is a need to compare the value of concentration determined with the concentration of aspirin given initially.  

0.02 grams is the initial concentration of aspirin mentioned in the question. The molar mass of aspirin is 240 g/mol.  

Therefore, the moles of aspirin will be,  

0.02 / 240 = 8.33 × 10^-5 moles  

The final volume of the diluted solution given is 10 ml or 0.01 liters.  

The molarity of aspirin in the diluted solution will be,  

c1 = 8.33 × 10^-5 / 0.01 = 8.33 × 10^-3 M or 0.00833 M

Now, the percent of salicylic acid in the product will be,  

c1 - c / c1 × 100

(0.00833 - 0.00768) / 0.00833 × 100 = 7.8 %

Absorbance is directly proportional to the concentration of the solution. The absorbance can be calculated if the molar absorptivity, path length, and concentration of the absorbing species are known.

The percent of salicylic acid in the solution is 7.8%

Given that:

Absorbance of the solution is = 1.07

Path length = 1 cm.

Applying Beer's Law,

A = ε b c

where,

c = concentration, A = absorbance, ε = constant, and b = path length

Now, putting the values in above equation

c = [tex]\dfrac{\text{A}}{\text {(e b)}}[/tex]

c = [tex]\dfrac{1.07}{139.32 \times 1}[/tex]        ( ε = 139.32)

c = 0.00768 M

Now, to calculate the percent of the salicylic acid in the solution, we will compare the given concentration of the aspirin.

As we know:

Given mass of aspirin = 0.02 g

Molar mass of aspririn = 240

Number of moles of aspirin = 0.02 / 240 = 8.33 x 10⁻⁵

Now, the molarity of aspirin is:

[tex]\text{Molarity}&= \dfrac{8.33 \times 10^{-5}}{0.01}\\\\\text{Molarity}&= 8.33 \times 10^{-5}[/tex]

Now, the percent of the salicylic acid is:

[tex]\dfrac{\text {C}_1 - \text C}{\text {C}_1 \times 100}[/tex]

[tex]\dfrac{(0.00833 - 0.00768)}{0.00833 \times 100}[/tex]

Percent of Salicyclic acid = 7.8%.

Thus, the percentage of the salicylic acid in the given solution is 7.8%.

To know more about Absorbance, refer to the following link:

https://brainly.com/question/17062521

A crystal of table salt (NaCl) is dissolved in water. Which of the following statements explains why the dissolved salt does not recrystallize as long as the temperature and the amount of water stay constant?

Na+ and Cl- ions lose their charges in the water.

Water molecules surround the Na+ and Cl- ions.

Na+ and Cl- ions leave the water through vaporization.

Water molecules chemically react with the Na+ and Cl- ions.

Your answer: -

Answer: B - Water molecules surround the Na+ and Cl- ions.

Answer:

By reacting carbon monoxide and hydrogen the formation of methanol takes place, the reaction is,

CO(g)+2H₂(g)⇔CH₃OH (g)

Based on the given reaction, one mole of methanol is obtained by reacting one mole of carbon monoxide (CO) with the two moles of hydrogen (H₂). It is mentioned in the question that for the reaction 500 mol of carbon monoxide and 750 moles of hydrogen are present.

Therefore for 500 moles of carbon monoxide, there is a requirement of 2 × 500 moles of hydrogen, which is equivalent to 1000 moles of hydrogen (H₂). However, only 750 moles of hydrogen is present. Therefore, the limiting reactant in the given case is H₂. The present moles of H₂ will react with 0.5 × 750 moles of CO = 375 mole of CO

The additional or excess concentration of CO, which is the excess reactant will be, 500-375 = 125 moles.

Answer:

A) 84 mL

Explanation:

use general gas equation P1×V1 / T1 = P2×V2/T2

rearrange the formula and solve for V2,it should give you V2= 84mL

Answer:

[tex]\large \boxed{\text{B) 84 mL}}[/tex]

Explanation:

We can use the Combined Gas Laws to solve this problem .

[tex]\dfrac{p_{1}V_{1} }{T_{1}} = \dfrac{p_{2}V_{2}}{T_{2}}[/tex]

Data

p₁ = 0.75 atm; V₁ = 120.0 mL; T₁ = 295 K  

p₂ = 1.25 atm; V₂ = ?;              T₂ = 345 K

Calculations

[tex]\begin{array}{rcl}\dfrac{p_{1}V_{1} }{T_{1}} & = & \dfrac{p_{2}V_{2}}{T_{2}}\\\\\dfrac{\text{0.75 atm $\times$ 120.0 mL}}{\text{295 K}} & = & \dfrac{\text{1.25 atm} \times V_{2}}{\text{345 K}}\\\\\text{0.305 mL} & = & \text{0.003 523V}_{2}\\V_{2}& =& \dfrac{\text{0.305 mL}}{0.003523}\\\\& = & \textbf{84 mL}\\\end{array}\\\text{The new volume of the gas is $\large \boxed{\textbf{84 mL}}$}[/tex]

Answer:

1.2 atm

Explanation:

Given data

If we consider ethylene gas to be an ideal gas, we can find the pressure of ethylene gas in the tank using Boyle's law.

[tex]P_1 \times V_1 = P_2 \times V_2\\P_1 = \frac{P_2 \times V_2}{V_1} = \frac{0.8atm \times 300L}{200.0L} = 1.2 atm[/tex]

Answer:

2

Explanation:

pH+pOH=14

- Hope that helps! Please let me know if you need further explanation.

Answer:

2

Explanation:

Ph+PoH=14

Answer:

The correct answer to the following question will be "0.0013%".

Explanation:

The given values are:

Weight of an empty dish = 1.0041 ± 0.0002 g

Weight of dish + sodium chloride (NaCl) = 3.2933 ± 0.0002 g

Weight of NaCl = 2.2892 ± 0.0002 g

Now,

Volume of the solution = 500.00 ± 0.05 ± 0.0002

                                      = 500.00 ± 0.0502 ml

So,

Molarity = [tex]\frac{W \ NaCl}{M \ NaCl} \times \frac{1000}{Volumes \ of \ solution}[/tex]

On putting the values in the above formula, we get

             = [tex]\frac{(2.2892\addeq +0.0002)}{58.440}\times \frac{1050}{(500.00+0.0502)}[/tex]

             = ([tex]3.917[/tex] ± [tex]0.0002[/tex]) × ([tex]2[/tex] ± [tex]0.0502[/tex])

             = ([tex]0.7834[/tex] ± [tex].00001004[/tex])

Now,

Absolute error = [tex]\frac{0.00001004}{0.7834}\times 100[/tex]

                         = [tex]0.0013[/tex]%

Answer: kg= 0.37

Explanation:

Use the molality formula.

M= m/kg

Answer:

Natural frequency

Explanation:

Answer:

Resonance

Explanation:

Explanation:

Entropy of a reaction ΔS∘rxn is the degree of disoderliness in a system. Gases generally have a higher degree of disorder compared to liquids. Hence for the reaction 2H2(g)+O2(g) ⟶ 2H2O(l), the entropy decreases sice the reactants are in the gaseous state and the products is in the liquid state of matter

Answer:

[tex]m_{nitrogen}=14g[/tex]

Explanation:

Hello,

In this case, since we are talking about a chemical reaction in which a compound having nitrogen and chlorine is decomposed into chlorine and nitrogen, we must remember that the law of conservation of mass must be obeyed, for that reason, we notice that the mass of the whole reactants must equal the mass of the whole products, as shown below:

[tex]m_{reactants}=m_{products}[/tex]

Next, we know there is only one single reactant and products are constituted by both chlorine and nitrogen:

[tex]m_{reactant}=m_{chlorine}+m_{nitrogen}[/tex]

In such a way, we can compute the mass of nitrogen as shown below:

[tex]m_{nitrogen}=m_{reactant}-m_{chlorine}=120.4g-106.4g\\\\m_{nitrogen}=14g[/tex]

Best regards.

Answer:

yes

Explanation:

Answer:

mass CO = 0.12166 g

Explanation:

Mass of CO = 0.12 grams

Explanation

Volume of CO gas = 117 mL = 0.117 L

Temperature of CO = 55.0 oC = 328 K

Assumption : Pressure of CO = atmospheric pressure = 1.0 atm

According to ideal gas law,

moles of CO = [(Pressure of CO) * (Volume of CO gas)] / [(R) * (Temperature of CO)]

where R = gas constant = 0.0821 L-atm/mol-K

moles of CO = [(1.0 atm) * (0.117 L)] / [(0.0821 L-atm/mol-K) * (328 K)]

moles of CO = 0.004345 mol

mass CO = (moles of CO) * (molar mass CO)

mass CO = (0.004345 mol) * (28.0 g/mol)

mass CO = 0.12166 g

Answer:

Magma

Explanation:

Magma is the hot liquid under earths surface

Answer:

C. precipitate formation.

Explanation:

options C is correct answer.

Answer:

C. precipitate formation.

Explanation: