Answer:
B. what happens when iron rusts in the presence of water
Explanation:
Chemistry is a branch of science involving the composition and changes of matter. In other words, a chemist, who is a trained specialist in the science of chemistry, seeks to answer questions related to properties of matter.
In this question, a chemist is most likely to study "what happens when iron rusts in the presence of water" because it involves a change in the chemical properties of a substance (iron) i.e. a chemical change. However, what happens when ice melts to liquid water is a physical change.
The compound 2-hydroxybiphenyl (o-phenylphenol) boils at 286 °C under 101.325 kPa and at 145 °C under a reduced pressure of
14 Torr. Calculate the value of the molar enthalpy of vaporization. Compare this value to that given in the CRC Handbook.
Answer: [tex]\Delta H_{vap}[/tex] = 55.1 kJ/mol
Explanation: Molar Enthalpy of Vaporization([tex]\Delta H_{vap}[/tex] ) is the energy needed to change 1 mol of a substance from liquid to gas at constant temperature and pressure.
For the 2-hydroxybiphenyl, there two temperatures and 2 pressures. In this case, use Clausius-Clapeyron equation:
[tex]ln\frac{P_{2}}{P_{1}}=\frac{\Delta H_{vap}}{R} (\frac{1}{T_{1}}-\frac{1}{T_{2}} )[/tex]
[tex]\Delta H_{vap}[/tex] is in J/mol:
1) Temperature in K
[tex]T_{1}=[/tex] 286 +273 = 559K
[tex]T_{2}[/tex] = 145 + 273 = 418K
2) Both pressure in Pa
[tex]P_{1}[/tex] = 101325Pa
[tex]P_{2}[/tex] = 14*133 = 1862Pa
Since molar enthalpy is in Joules, gas constant R is 8.3145J/mol.K
Replacing into the equation:
[tex]ln\frac{1862}{101325}}=\frac{\Delta H_{vap}}{8.3145} (\frac{1}{559}-\frac{1}{418} )[/tex]
[tex]ln(0.0184)=\frac{\Delta H_{vap}}{8.3145} (\frac{141}{233662} )[/tex]
[tex]\Delta H_{vap}=\frac{-3.9954*1942782.7}{-141}[/tex]
[tex]\Delta H_{vap}=55051.02[/tex]
[tex]\Delta H_{vap}=55051.02[/tex]
[tex]\Delta H_{vap}=55.1[/tex] kJ/mol
Using those values, molar enthalpy is 55.1 kJ/mol
Comparing to the CRC Handbook, which is [tex]\Delta H_{vap}=71[/tex] kJ/mol:
[tex]\frac{55.1}{71}[/tex] = 0.78
The calculated value is 0.78 times less than the CRC Handbook.
What was Albert Einstein's contribution to our understanding of the
photoelectric effect?
A. He described the relationship between energy and mass.
B. He described photons as little packets of electrons.
C. He described electricity as moving electrons.
D. He described light as little packets called photons.
Answer: The Answer Is D, He described light as little packets called photons.
Explanation:
The contribution of Albert Einstein to our understanding of the photoelectric effect is he described light as little packets called photons. The correct option is D.
Who is Albert Einstein?The theory of relativity, which Albert Einstein developed and is rightfully famous for, transformed our understanding of space, time, gravity, and the cosmos.
Along with his work on relativity, the physicist established the scientific principles behind items like paper towels, lasers, and other everyday items.
Since Einstein first suggested using the use of light quanta to clarify the photoelectric impact, quantum theory accurately portrays the photoelectric impact. The quantum theory of radiation gives this concept a formal formulation.
Therefore, the correct option is D. He described light as little packets called photons.
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PLEASE ANWSER FAST! Gus is performing an experiment on cells. First he places the cells in a container of water and salt. When he checks some of the cells under a microscope, he sees that they are beginning to shrivel. What would most likely stop the cells in the liquid from shriveling? adding more water to the container adding more salt to the container increasing the number of cells in the container decreasing the number of cells in the container
Answer:
adding more water to the container
Explanation: because it would cause it to soak up the fluid to created a substance again
Answer:
adding more water to the container and iflamates the cells
Explanation:
A 0.500 g sample of tin (Sn) is reacted with oxygen to give 0.534 g of product. What is the empirical formula of the oxide?
Answer:
[tex]Sn_2O[/tex]
Explanation:
Hello,
In this case, given the mass of the sample and mass of tin we can compute the mass of oxygen via:
[tex]m_O=0.534g-0.500g=0.034g[/tex]
Thus, by using the atomic bas of tin and oxygen we can compute their moles:
[tex]n_{Sn}=0.500gSn*\frac{1molSn}{118.8gSn} =0.00421mol\\\\n_O=0.034gO*\frac{1molO}{16gO}=0.002125mol[/tex]
Next, we need to divide both moles by the moles of oxygen as those are the smallest in order to compute the subscript in the chemical reaction:
[tex]Sn=\frac{0.00421}{0.002125}=2\\ \\O=\frac{0.002125}{0.002125}= 1[/tex]
Therefore, empirical formula of the oxide should be:
[tex]Sn_2O[/tex]
Best regards.
The measurement 3.8 x 10^3 g could also be written as
Right now it's written in scientific notation, so you can just move the decimal place in 3.8 to the right 3 times (as it is times 10 to the third power) to get 3,800g.
The measurement 3.8 x 10³ grams could also be written as 3.8 kilograms.
What is a unit of measurement?A unit of measurement is a specified magnitude of a quantity that is established and used as a standard for measuring other quantities of the same kind. It is determined by convention or regulation.
As given in the problem we have to convert the measurement of 3.8 x 10³ grams into some different units,
1000 grams = 1 kilograms
1 gram = 1 /1000 kilograms
3.8 x 10³ grams = 3.8 x 10³ ×1 /1000 kilograms
=3.8 kilograms
Thus, the measurement 3.8 x 10³ grams could also be written as 3.8 kilograms.
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100.0 mL of a 0.500 M solution of KBr is diluted to 500.0 mL. What is the new concentration of the solution
Answer:
0.1 M
Explanation:
The following data were obtained from the question:
Initial volume (V1) = 100 mL
Initial concentration (C1) = 0.5 M
Final volume (V2) = 500 mL
Final concentration (C2) =?
Using the dilution formula C1V1 = C2V2, the new concentration of the solution can be obtained as follow:
C1V1 = C2V2
0.5 × 100 = C2 × 500
50 = C2 × 500
Divide both side by 500
C2 = 50/500
C2 = 0.1 M
Therefore, the new concentration of the solution is 0.1 M
The new concentration of the solution of KBr that was diluted to 500mL is 0.1M
HOW TO CALCULATE CONCENTRATION:
The concentration of solution that was diluted can be calculated using the formula as follows:C1V1 = C2V2Where:
C1 = original concentration (M)C2 = diluted concentration (M)V1 = original volume (mL)V2 = diluted volume (mL)According to this question, 100.0 mL of a 0.500 M solution of KBr is diluted to 500.0 mL. The new concentration can be calculated as follows:0.500 × 100 = C2 × 50050 = 500C2C2 = 50 ÷ 500C2 = 0.1MTherefore, the new concentration of the solution of KBr that was diluted to 500mL is 0.1M.Learn more at: https://brainly.com/question/10720472?referrer=searchResults
Which device involves the use of plasma in technology? arc welder diesel engine incandescent lightbulb battery-operated flashlight
Answer:
arc welder involves use of plasma in technology
The device involves the use of plasma in technology is "arc welder"
What is plasma ?The 4th phase of matter, after solid, liquid, as well as gas, often been referred to as plasma. Inside a particular substance that is solid, liquid, or even gaseous, the electrons typically stick with almost the unique atomic nucleus.
What is arc welder?Using electricity to generate sufficient heat to dissolve metal as well as then allowing the melted metals to cool, arc welding would be a technique for joining metals together.
Arc welding employs the plasma technology principle because the gas would be ionized.
Therefore, the correct answer will be option (a).
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When 14.8 g KOH is dissolved in 85.6 g of water in a coffee-cup calorimeter, the temperature rises from 19.3 °C to 32.76 °C. What is the enthalpy change per gram of potassium hydroxide dissolved in the water?
Answer:
This question is incomplete, the complete question is; assuming that the solution has a specific heat of 4.18 J/g°C
The answer is 381.67 J/g
Explanation:
Enthalpy change denoted by ΔH can be calculated using the formula;
ΔH = m × c × ΔT
Where; m= mass of reactants
c= specific heat
ΔT = change in temperature
ΔT = T2 - T1
ΔT = 32.76 - 19.3
ΔT = 13.46 °C
mass of reactants= 85.6 + 14.8 = 100.4g, c = 4.18J/g°C
Hence; ΔH = m × c × ΔT
ΔH = 100.4 × 4.18 × 13.46
ΔH = 5648.78J
Enthalpy change per gram of potassium hydroxide dissolved in the water is;
ΔH = 5648.78/14.8
ΔH = 381.67 J/g
The enthalpy change per gram of potassium hydroxide dissolved in the water is 382 J/g
How to determine the heat Mass (M) = 14.8 + 85.6 = 100.4 gInitial temperature (T₁) = 19.3 °C Final temperature (T₂) = 32.76 °CChange in temperature (ΔT) = 32.76 – 19.3 = 13.46 °C Specific heat capacity (C) = 4.184 J/gºC Heat (Q) =?
Q = MCΔT
Q = 100.4 × 4.184 × 13.46
Q = 5654.19 J
How to determine the enthalpy change ΔHHeat (Q) = 5654.19 JMass of KOH (m) = 14.8 gEnthalpy change (ΔH) =?ΔH = Q / g
ΔH = 5654.19 / 14.8
ΔH = 382 J/g
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Pure water can be consumed in a chemical reaction, resulting in the formation of a new
product. Refer to paragraph four. What type of change is this?
A. A physical change
B. A chemical change
C. A mixture change
D. A compound change
Is gasoline evaporated, gasoline, burned water frozen and water heated up a chemical change
Answer:
as gasoline is evaporated, this gasoline still remains as gasoline but in gaseous form when gas is being burned .
The best thermometer to use where temperatures drop below -39°C (-38.2°F) is:_______.
Answer:
The best thermometer to use for this temperature is the alcohol-in-a -glass thermometer.
Explanation:
The alcohol thermometer is a type of thermometer which uses ethanol as its thermometric liquid. This has some advantages at low temperatures because ethanol freezes at about −114.9 °C that is (−174.82 °F).
Due to its low freezing point, it can still function effectively as a thermometric liquid, expanding and contracting properly based on the applied heat, when dealing with temperature measurements that are at about -38.2°F.
write the number in scientific notation 1123
Discuss and Implement the Price Adjustment Strategies in the current market. Apply each strategy with 3 examples along with the picture. This question is related to Marketing.
Answer:
There are many different price adjustment strategies which can be implemented in the current market.
Explanation:
Psychological pricing:
Psychological pricing is a strategy in which the price of a product is displayed with mostly one cent difference so the whole number shown is less by $1 and this difference can get higher if the price of the product is more.
Example 1: The price for a toy in a toy shop is $4.99, if rounded this will be $5 but the whole number visible is $4.
Example 2: The price of a laptop is $193, this again is nearly $200 but the price is reduced by $7 in order to influence their customers into buying the product.
Example 3: The price of a car is $35,995, this again is about $36,000 but the buyer may be influenced by this technique and result in purchasing the product with such price.
Geographical Pricing:
Geographical pricing is a strategy where different prices are charged in different outlets, this strategy is made keeping in mind the purchasing power of the locality, if the local people can pay higher price for a product then the price is high there but same product may have a lower price in an area where people can not pay high price.
Example 1: Price of a T-shirt is $15 in a posh area while the price of the same T-shirt is $5 in an area with poor locality.
Example 2: Price of a hair brush is $10 in a poor area while the same brush is available in a posh area at a rate of $35.
Example 3: Price for a food item is $6 in a restaurant in posh area while the same burger is available for $3 in a restaurant in a poor area.
An atom with a mass number of 27 has 14 neutrons. What element is the atom?
Answer:
aluminum i think
Explanation:
what is the balanced chemical equation when solid calcium oxide and carbon dioxide gas are formed by the decomposition of solid calcium carbonate (CaCO3)
Give the name of HI as an acid and as a binary compound
Answer:
HI is a diatomic molecular compound known as hydrogen iodide or hydroiodic acid. It is a strong acid.
john has a solution with a pH of 12.21. what is the hydrogen ion concentration of this solution?
Answer:
In this way, ph is determined by hydrogen ion concentration . In the case of neutral solution [H+] =10-7 which we call a ph of 7. This means, for example, that a hydrogen-ion concentration of a solution with a ph of 4 is 10-4 mol/l, meaning it contains 0.0001 mole of hydrogen ion in a solution of 1 liter.
The scientific method is great, but how do you think we answer the questions which cannot be tested with an experiment?
Answer:
We do something called hypothesis
Answer:
1. Make an observation.
2. Ask a question.
3. Propose a hypothesis.
4. Make predictions.
5. Test the predictions.
6. Iterate.
and if it can't be trsted the you did something wrong
Explanation:
The scientific method
At the core of biology and other sciences lies a problem-solving approach called the scientific method. The scientific method has five basic steps, plus one feedback step:
Make an observation.
Ask a question.
Form a hypothesis, or testable explanation.
Make a prediction based on the hypothesis.
Test the prediction.
Iterate: use the results to make new hypotheses or predictions.
The scientific method is used in all sciences—including chemistry, physics, geology, and psychology. The scientists in these fields ask different questions and perform different tests. However, they use the same core approach to find answers that are logical and supported by evidence.
Scientific method example: Failure to toast
Let's build some intuition for the scientific method by applying its steps to a practical problem from everyday life.
What is the final volume of argon gas if 2.5 L at 94.0 kPa is compressed to a pressure of 207 kPa
Answer:
1.1 L
Explanation:
Volume and pressure are inversly proportional to each other meaning as volume increase, pressure decreases or the other way around. Use the equation V1P1=V2P2. So, it'll be (2.5L)(94.0kpa)=(207kPa)(V2). Thereby it is (2.5*94.0)/207= V2 = 1.1L. Don't forget your sigfigs which will be to 2 sigs.
An advertisement for a new fish food claims that lab studies show that fish grew three inches in three weeks while eating the food. Travis wondered if the food was worth the extra cost.
Answer: To evaluate the claim in the advertisement, Travis should look at the data for the control group to see how much the fish grew without the new food.
Explanation:
A 4.00 (±0.01) mL Class A transfer pipet is used to transfer 4.00 mL of a 0.302 (±0.004) M Cu2+ stock solution to a 100.00 (±0.08) Class A volumetric flask. Deionized water is used to bring the flask to volume. Calculate the concentration of the diluted soluion in the volumetric flask and report its absolute uncertainty.
Answer:
concentration of diluted solution = 0.0125 ( ± 0.0002)M
Uncertainty = ± 0.0002
Explanation:
Given that
Initial volume of Cu2+ = 4.00 (±0.01) mL
Initial molarity 0f Cu2+ = 0.302 (±0.004) M
transferred to 100.00 (±0.08) Class A volumetric flask
first we get amount of water added
100.00 (±0.08) - 4.00 (±0.01) = 96 ± (0.09)
Now according to law of dilution
The concentration of Cu2+ after adding water
M1V1 = M2V2
we substitute
0.302 (±0.004) * 4.00 (±0.01) = x * 96 ± (0.09)
Now the multiplication of two digits with uncertainty is
(0.004/0.302) * 100 = 1.32% ; (0.01/4.00) * 100 = 0.25%
= [0.302 ( ± 1.32% )] * [ 4.00 ± (0.25%)]
= 1.208 ±(1.57%)
1.57/100 * 1.208 = 0.0189
so
= (1.208 ± 0.0189)
now substitute in our previous equation
1.208 ± (0.0189) = x * 96 ± (0.09)
x = 1.208 ± (0.0189) / 96 ± (0.09)
{ 0.09/96 * 100 = 0.094% }
so x = 1.208 ± (1.57%) / 96 ± (0.094% )
x = 0.0125 ± ( 1.664)
now( 1.664/100 * 0.0125)
= ± 0.000208
Hence
concentration of diluted solution = 0.0125 ( ± 0.0002)M
Uncertainty = ± 0.0002
I WILL mARK U BRAINLLYIST
Scientists in a particular fieScientists in a particular field strive for the same quality of work because they know their peers will be reviewing their scientific claims. What does this review process help ensure?
standards of the profession
publication in scientific journals
resistance to new information
access to university databases
A change in the number of neutrons in an atom will change an isotope. What will happen when the number of protons changes in an atom?
A cube has an edge length of 9 cm .
If it is divided up into 1-cm cubes, how many 1-cm cubes would there be?
Answer:
9^3 i think so like 279
Explanation:
blah
Which of the following is equal to an impulse of 18 units?
O A. Force = 10, time = 2
B. Force = 0.1, time = 18
O C. Force = 6, time = 3
OD. Force = 7, time = 3
Answer:
the answer is C. this is because 6 times 3 is 18
What is Avogadro's number?
the number of atoms in exactly 14.00 g of carbon-12
the number of atoms in a kilogram of any substance
the number of atoms, molecules, ions, formula units, or other particles in a mole of a substance
the number of atoms, molecules, ions, formula units, or other particles in a gram of a substance
Answer:
C
Explanation:
its not A since its actually the atoms in exactly 12g of crabon-12
-not B since its grams not kilograms
-not D since it says "gram" which would mean that we measure the particles in a gram instead of a mole
Avogadro's number is the number of atoms, molecules, ions, formula units, or other particles in a mole of a substance. Therefore, option (c) is correct.
What is Avogadro's number?The Avogadro constant commonly denoted [tex]N_A[/tex] is the proportionality factor that the number of constituent particles such as molecules, atoms, or ions in one mole of a sample.
Avogadro's number is a constant with an exact value of 6.022 × 10²³ reciprocal moles. Avogadro's number is named by Stanislao Cannizzaro after the Italian scientist Amedeo Avogadro, who explained it four years after Avogadro's death.
The numerical value of the Avogadro constant is in reciprocal moles, a dimensionless number known as the Avogadro number. The value of the Avogadro constant, the mass of one mole of a chemical compound, in grams.
It is numerically equal to the average mass of one molecule of the compound in daltons. One dalton is 1/12 of the mass of one carbon-12 atom, which is the mass of one nucleon.
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during a rainy spring, where are you most likely to find surface runoff
Answer:On a sloped parking lot
Explanation:
Helium is more reactive than magnesium.
TRUE
FALSE
Answer: FALSE
Explanation: Magnesium is more reactive.
Hope this helps!
Answer:
False
Explanation:
Magnesium is more reactive.
is a light bulb chemical or physical change. State evidence why
Answer:
It is a chemical change.
Explanation:
When the electricity is off, the filament cools down to its original physical state. This physical process repeats every time the light is turned on and off. However, if the bulb is cracked and air is introduced, the oxygen in the air reacts with the tungsten filament which then undergoes a chemical change.
Alkynes are reduced to trans alkenes by a process called dissolving metal reduction. The reaction uses sodium or lithium metal as the reducing agent and liquid ammonia as the solvent. The method is specific in the formation of trans alkenes from alkynes. The method involves two successive transfers of single electrons from the alkali metal to the triple bond, with abstraction of protons from the ammonia solvent.Draw curved arrows to show the movement of electrons in this step of the mechanism.Arrow-pushing Instructions
Answer:
Explanation:
The movement of the electrons is illustrated in the picture attached to this answer. It is a four-step reaction mechanism.
First STEP: The first step involves the transfer of an electron from sodium to form a radical anion.
Second STEP: This radical anion then removes a proton/hydrogen from ammonia in a bid to neutralize itself (hence the hydrogen becomes bonded to the anion).
Third STEP: The sodium (from NaNH₂ formed) transfers an electron again to produce a vinyl carbanion.
Fourth STEP: The carbanion then removes a proton/hydrogen from ammonia (like in the second step) to form a neutral trans-alkene.
NOTE: The circled numbers denote each step while the mechanism on the left represents the use of any alkyl group (R and R') while the mechanism on the right assumes both alkyl groups are methyl. Hence, 2-butyne started the reaction and the final product was trans-2-butene.