Answer:
A. 4.0 mol
Explanation:
Divide 16 g by the molar mass of He, which is 4.0 g/mol.
16 g / 4.0 g/mol = 4.0 mol
visible light travels from place to place as a
Answer:
Light can travel in three ways from a source to another location: (1) directly from the source through empty space; (2) through various media; (3) after being reflected from a mirror.
Explanation:
Compare Dalton’s and Democritus’ ideas.
Answer:
please give me brainlist and follow
Explanation:
The key difference between Democritus and Dalton atomic theory is that the Democritus atomic theory is an ancient theory that scientists later refined and elaborated whereas Dalton atomic theory is a comparatively modern, scientific theory that we cannot discard due its important statements.
A student dissolves 10.7 g of lithium chloride (LiCl) in 300. g of water in a well-insulated open cup. He then observes the temperature of the water rise from 22.0 °C to 28.6 °C over the course of 3.8 minutes. Use this data, and any information you need from the ALEKS Data resource:
LiCl(s) rightarrow Li+(aq) + Cl-(aq)
You can make any reasonable assumptions about the physical properties of the solution. Note for advanced students: it's possible the student did not do the experiment carefully, and the values you calculate may not be the same as the known and published values for this reaction.
1) Is this reaction exothermic, endothermic, or neither?
2) If you said the reaction was exothermic or endothermic, calculate the amount of heat that was released or absorbed by the reaction in this case.
3) Calculate the reaction enthalpy delta Hrxn per mole of LiCl.
Answer:
1) Exothermic.
2) [tex]Q_{rxn}=-8580J[/tex]
3) [tex]\Delta _rH=-121.0kJ/mol[/tex]
Explanation:
Hello there!
1) In this case, for these calorimetry problems, we can realize that since the temperature increases the reaction is exothermic because it is releasing heat to solution, that is why the temperature goes from 22.0 °C to 28.6 °C.
2) Now, for the total heat released by the reaction, we first need to assume that all of it is absorbed by the solution since it is possible to assume that the calorimeter is perfectly isolated. In such a way, it is also valid to assume that the specific heat of the solution is 4.184 J/(g°C) as it is mostly water, therefore, the heat released by the reaction is:
[tex]Q_{rxn}=-m_{Total}C(T_2-T_1)\\\\Q_{rxn}=-(300g+10.7g)*4.184 \frac{J}{g\°C} (28.6\°C-22.0\°C)\\\\Q_{rxn}=-8580J[/tex]
3) Finally, since the enthalpy of reaction is calculated by dividing the heat released by the reaction over the moles of the solute, in this case LiCl, we proceed as follows:
[tex]\Delta _rH=\frac{Q_{rxn}}{n_{LiCl}} \\\\\Delta _rH=\frac{-8580J}{10.7g*\frac{1mol}{150.91g} }*\frac{1kJ}{1000J} \\\\\Delta _rH=-121.0kJ/mol[/tex]
Best regards!
1.Are forests a renewable or non-renewable resource? Give reasons for both possibilities
Answer:
Forests are renewable
Explanation:
Forests can grow again, but it takes forever to grow a new one so it shouldn't be taken for granted! You can remake a whole new forest, but it will take around 50 years and a lot of animals will die without them before that time comes!
But then again, it could be a non-renewable resources; because it takes so long to grow a new one!
Hope this helps!
3. The name of the functional group in the following compound
CH3 - CH2 - CH2 - CH-CH2 - CH3
1
CH3 – CH2
a. Methyl
b. Ethyl
C. Propyl
d. Isopropy!
Answer: a.) Methyl would be the answer.
Explanation:
What happens if more solute is added to a saturated solution?
Answer:
A saturated solution is a mixture in which the maximum amount of a given solute has been dissolved into the solvent. ... At this point adding more solute will not change the concentration of the solution; adding more solute will simply result in more solid at the bottom of the solution.
Answer:
will not change
Explanation:
A saturated solution is a mixture in which the maximum amount of a given solute has been dissolved into the solvent. ... At this point adding more solute will not change the concentration of the solution; adding more solute will simply result in more solid at the bottom of the solution.
A 0.6467-g portion of manganese dioxide was added to an acidic solution in which 1.1701 g of a chloride-containing sample was dissolved. Evolution of chlorine took place as a consequence of the following reaction: After the reaction was complete, the excess was collected by filtration, washed, and weighed, and 0.3104 g was recovered. Express the results of this analysis in terms of percent aluminum chloride.
Answer:
29.39% of AlCl₃ in the sample
Explanation:
Based on the reaction:
MnO₂(s) + 2Cl⁻ + 4H⁺ → Mn²⁺ + Cl₂(g) + 2H₂O
We can find the amount of chloride in solution with the amount of MnO₂ that reacted as follows:
Initial mass MnO₂ = 0.6467g
Recovered mass = 0.3104g
Mass that reacted = 0.6467g - 0.3104g = 0.3363g
Moles MnO₂ -Molar mass: 86.9368g/mol-:
0.3363g * (1mol / 86.9368g) = 3.868x10⁻³ moles MnO₂
Moles Cl⁻:
3.868x10⁻³ moles MnO₂ * (2mol Cl⁻ / 1mol MnO₂) = 7.737x10⁻³ moles Cl⁻
Moles of AlCl₃ and mass -Molar mass AlCl₃: 133.34g/mol-:
7.737x10⁻³ moles Cl⁻ * (1mol AlCl₃ / 3mol Cl⁻) = 2.579x10⁻³ moles AlCl₃
2.579x10⁻³ moles AlCl₃ * (133.34g / mol) =
0.3439g of AlCl₃ are present in the sample.
The percent is:
0.3439g of AlCl₃ / 1.1701g * 100 =
29.39% of AlCl₃ in the sampleWhich of the following must be overcome by a rocket's thrust?
Answer:
the payloads weight
Explanation:
a p e x on the ground stream
Answer:
The payload's weight
Explanation:
i just took the test on a pex :)
These properties best describe which body (Gases Surface, 75%H, 25% He, Zones)
(18 Points)
Planet
or
Sun
NO LINKS
Answer:sun
Explanation:The Sun is the star at the center of the Solar System. It is a nearly perfect sphere of hot plasma, heated to incandescence by ... When hydrogen fusion in its core has diminished to the point at which the Sun is no longer in . Sunlight on the surface of Earth is attenuated by Earth's atmosphere, so that less power arrives
Lab: Measuring pH Table or
Lab Report please ( just link it ) please
Answer:
sorry my phone died lol but here are the answers
<3
1. If I have 5 moles of a gas at a pressure of 7.6 atm and a volume of 12 liters, what is the temperature?
Answer:
221.22K or -51°C
Explanation:
We will be using the Ideal Gas Law to calculate the temperature of the gas. It is a mathematical relationship that describes the behavior of ideal gas ample for any combo of varying pressure, volume, temperature, and # of moles (n). It is derived by combing Boyle's Law, Charles' Law, Gay-Lussac's & Avogadro's Law.
Note: As always, remember that temperature must be in Kelvin not Celsius when using this equation.
Ideal Gas Law: [tex]PV = nRT[/tex], where P = pressure, V = volume (in Liters), n = # of moles, R = the ideal gas constant, and T = temperature (in Kelvin).
Based on the problem, we are given the pressure, volume, and # of moles. We are asked to find the temperature. What about R you ask? Well, R is a constant that is the value of 1 mole of gas at STP. R has various values depending on the pressure units. In this case, our pressure is in atm so the R value = 0.0821.
Onto the math - all that needs to be done now is to plug and chug. Plug in the given values to find the temperature:
Set up: [tex](7.6 atm)(12L) = (5 mol)(0.0821 L*atm/(mol*K))(T)[/tex]
==> [tex]T = \frac{(7.6 atm)(12L)}{(5 mol)(0.0821 L*atm/(mol*K))}[/tex]
==> T = 221.17K
The answer is 221.17K. To convert into Celsius, subtract by 273.15 to get -50.99 or -51°C.
PLEASE ASNWR ASAP
If I have a 50 liter container that holds 45 moles of gas at a pressure of 2.66 x 104 mmHg, what is the
temperature inside the container? ** convert pressure to atm**
Help please thank youu
Answer:
The KE increases.
Explanation:
KE=1/2(mv²)
So, as the velocity increases, kinetic energy also increases.
What is the value for AG at 5000 K if AH = -220 kJ/mol and S= -0.05 kJ/(mol-K)?
A. -195 kJ
B. -470. kJ
C. 30 kJ
D. 470 kJ
Answer:
C. 30 kJ
Explanation:
Hello there!
In this case, in agreement to the thermodynamic definition of the Gibbs free energy, in terms of enthalpy of entropy:
[tex]\Delta G= \Delta H-T\Delta S[/tex]
It is possible to calculate the required G by plugging in the given entropy and enthalpy as shown below:
[tex]\Delta G=-220kJ/mol-5000K*-0.05kJ/mol*K\\\\\Delta G=30kJ/mol[/tex]
Therefore, the answer is C. 30 kJ .
Best regards!
Cosmic rays are
A. High energy radiation produced in the ozone layer.
B. High energy radiation produced by the earth’s core.
C. None of these.
D. High energy radiation produced by the sun.
A. High energy radiation produced in the ozone layer. (:
Which metals will switch in this single replacement reaction Zn + MgO -->
a. Mg and Zn
b. Zn and O
c. Mg and O
d. This is not a single replacement reaction
Answer:
D
Explanation:
Magnesium is more reactive than zinc so no reaction will take place
What is the best method of separating the mixture of sand and fine salt?
By using filtration, the sand and fine salt can be effectively separated based on their difference in particle size, providing a clean separation of the two components.
Filtration is a separation technique that takes advantage of the difference in particle size between sand and salt. It involves passing the mixture through a porous material, such as filter paper or a filter funnel, which allows the liquid (saltwater) and small salt particles to pass through while retaining the larger sand particles.
Here's how the filtration process can be carried out:
1. Set up a filter apparatus with a funnel and filter paper or a filter flask.
2. Place the mixture of sand and salt in a beaker or a flask.
3. Slowly pour the mixture into the filter paper or funnel, allowing the liquid (saltwater) to pass through while retaining the sand on the filter paper.
4. Once the liquid has passed through completely, the sand will be left behind on the filter paper or in the filter flask.
5. Carefully remove the sand from the filter paper or filter flask, and the saltwater solution can be collected separately.
For more such questions on filtration
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What will be the pH of a buffer solution containing an acid of pKa7.5, with an acid concentration exactly one fourth of that of the conjugate base
Answer: pH of buffer solution is 8.1
Explanation:
The formula for the Henderson–Hasselbalch equation is:
[tex]pH=pK_a+\log\frac{[A^-]}{[HA]}[/tex]
[tex]pH[/tex] is the concentration of [tex][H^+][/tex]
[tex]pK_a[/tex] is the acid dissociation constant,
[tex]A^-[/tex] and [tex]HA[/tex] are concentrations of the conjugate base and starting acid.
Putting in the values we get:
[tex]pH=7.5+\log\frac{x}{\frac{x}{4}}[/tex]
[tex]pH=8.1[/tex]
Thus pH of buffer solution is 8.1
if a gas sample has a pressure of 30.7 kPa at 273 K, what does the temperature have to decrease to lower the pressure to 28.4 kPa?
253K
268K
262K
4. What is the molarity of a solution that contains 65g of sodium nitrate in 750? ml of solution?
Answer:
1.02 M
Explanation:
Solution contains 65g of sodium nitrate
Volume of solution = 750 ml
Now, Molar mass of sodium nitrate from online values = 84.9947 g/mol
Thus, it means 84.9947 g/mol of sodium nitrate dissolved in 1000 mL of water will be equal to 1 M molarity.
Thus;
Molarity of solution = (65/750) × (1000) × (1/84.9947) = 1.02 M
When a balloon is blown up then let go air molecules rush out of the balloon and join the air molecules in earths atmosphere what happens to the enthalpy in the balloon?
Answer: It decreases
Answer: It decreases.
Explanation: a p e x :)
which bond does water atom share
Answer:
Covalent bonds
Explanation:
A water molecule consists of two atoms of hydrogen linked by covalent bonds to the same atom of oxygen. Atoms of oxygen are electronegative and attract the shared electrons in their covalent bonds.
What type of Weathering is important to sand storms on Mars? Physical or
Chemical?
Why would 3D printing be important on Mars and why would you use material from the surface of Mars.
We could "print" things that we need on Mars.
We could print things that we need on Mars and use material that is already on the planet
It would be so cool
The cost would be less expensive.
Answer:
1. Physical Weathering
2. Option B
Explanation:
1. Physical weathering
On Mars, there are two types of weathering agents a) wind and b) acid fog. Thus, they will carry out only physical weathering
2. Option B
3D can be used to produce things that are required on the Mars and also the locally available raw material can be used for printing thereby saving the cost.
Which salt preparation uses a burette and a pipette
potassium chloride from potassium hydroxide and hydrochloric acid
If objects with a greater mass have greater gravitational pull, why is our solar
system, Sun, planets and asteroids, NOT pulled into Alpha Centauri A?
Answer:
It's too far away
Explanation:
According to classical mechanics, gravitational pull is inversely proportional to the distance squared; as the distance increases, the gravitational pull decreases at a faster and faster rate. Since Alpha Centauri A is a few lightyears (Tens of trillions of kilometers away), without even needing to calculate the force of gravity, it is very miniscule.
A buffered solution _______. Select the correct answer below: fails to keep hydronium and hydroxide ion concentrations nearly constant when strong acids or bases are added. maintains a constant or nearly constant pH when small amounts of strong acids or bases are added. acts to keep the hydroxide ion concentration nearly constant. acts to keep the hydronium ion concentration nearly constant.
The correct option for the given question about Buffer Solution is Option B) which is maintains a constant or nearly constant pH when small amounts of strong acids or bases are added.
What is a Buffer Solution?When a little quantity of acid or base is diluted or added, the buffer solution undergoes very slight variations in its hydrogen ion concentration (pH). pH may be maintained in buffer solutions, which are mixtures of a weak acid and its conjugate base or a weak base and its conjugate acid.Acidic and alkaline buffers are the two main groups into which buffer solutions are commonly categorized.A weak acid and its salt are combined with a strong base to create an acidic buffer, which has an acidic pH.A weak base, its salt, and a strong acid are combined to create an alkaline buffer, which has a basic pH.
Thus we conclude that when weak acids or bases are supplied in small amounts, the pH remains steady or almost constant.
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I have a lab report I have to do for Chemistry on Edge, the lab is on Enthalpy.
please let me know if you need further information.
Answer:
I need further information.
Explanation:
Extra information is needed for you to know the correct information.
What is Enthalpy?It is a thermodynamic quantity that is equal to the total heat content of a system. It is equal to the internal energy of the system plus the product of pressure and volume.
Enthalpy is nothing but energy and they are of 4 types in thermodynamics-
1. Internal Energy, U
2. Heat enthalpy, H
3. Helmholtz enthalpy, A
4. Gibb's Free enthalpy, G
The total energy of a system cannot be measured directly because the internal energy contains components that are unknown, not easily accessible, or are not of interest in thermodynamics. Generally, a change in enthalpy is the expression for measurements at constant pressure because it simplifies the information of energy transfer.
Therefore, Extra information is needed for you to know the correct information.
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One liter of gas A at 1.0 atm pressure has a temperature of 25°C while the same volume and pressure of gas B has a temperature of 50°C. What else do you know about these two gases?
A) There are twice as many moles of gas B than gas A.
B) Gas A has twice the molar mass of gas B.
C) Gas A has more kinetic energy than gas B.
D) Gas B has more kinetic energy than gas A.
Answer:
b
Explanation:
What type of chemical reaction is this?
2Na + 2H20 - 2NaOH + H2
Rusting is a chemical reaction between Iron metal [Fe(s)] and oxygen gas [O2(g)] in a slightly acidic environment. Rusting is actually a multi-step reaction, however it has the net overall reaction of:
4Fe+3O2--->2FeO3
If 100.0 g of iron metal are converted into rust, how many moles of rust will have formed? (Assume unlimited oxygen gas.)
*Hint* You already converted 100.0 g of Fe into moles of Fe in a previous question, start there.
Answer:
0.895 mole of Fe₂O₃.
Explanation:
We'll begin by calculating the number of mole in 100 g of Fe. This can be obtained as follow:
Molar mass of Fe = 56 g/mol
Mass of Fe = 100 g
Number of mole of Fe =?
Mole = mass / molar mass
Number of mole of Fe = 100 / 56
Number of mole of Fe = 1.79 mole
Finally, we shall determine the number of mole of Fe₂O₃ produced by the reaction of 100 g (i.e 1.79 moles) of Fe. This can be obtained as follow:
4Fe + 3O₂ — > 2Fe₂O₃
From the balanced equation above,
4 moles of Fe reacted to produce 2 moles of Fe₂O₃.
Therefore, 1.79 moles of Fe will react to produce = (1.79 × 2)/4 = 0.895 mole of Fe₂O₃.
Thus, 0.895 mole of Fe₂O₃ was obtained from the reaction.