Answer:
526g is the mass of this sample
Explanation:
To solve this question we must, as first, find the molar mass of Al₂(Cr₂O₇)₃ using the periodic table. The molar mass is defined as the mass of this compound per mole. With this value we can find the mass in 0.750 moles as follows:
Molar mass Al₂(Cr₂O₇)₃
2Al = 2*26.98g/mol = 53.96g/mol
6 Cr = 6*51.9961g/mol = 311.9766g/mol
21 O = 21*15.999g/mol = 335.979g/mol
53.96g/mol + 311.9766g/mol + 335.979g/mol
= 701.9156g/mol
The mass of 0.750 moles is:
0.750 moles * (701.9156g / mol) =
526g is the mass of this sampleYou have to prepare a pH 5.00 buffer, and you have the following 0.10 M solutions available: HCOOH (pka=3.74), HCOONa, CH3COOH (pka=4.74), CH3COONa, HCN (pka=9.31), and NaCN. Which solutions would you use?
Answer:
CH3COOH - CH3COONa since its pKa is closest to the required pH.
Explanation:
Hello there!
In this case, in agreement with the theory of buffers as solutions able to withstand severe pH changes due to the addition of acidic or basic substances, it is possible to set up a generation equilibrium expression for the acids herein given:
[tex]Ka=\frac{[A^-][H_3O^+]}{[HA]}[/tex]
Which leads to the Henderson-Hasselbach equation:
[tex]pH=pKa+log(\frac{[A^-]}{[HA]} )[/tex]
Thus, since all the buffers have [A-]=[HA]=0.10M, the log part becomes 0 and therefore the best buffer will have the closest pKa to the required pH, which is CH3COOH - CH3COONa since its pKa is 4.74.
Best regards!
[tex]CH_3COOH\; and\; CH_3COONa[/tex] can be used to prepare a pH buffer, if 0.10 M solution available of the solutions.
What is buffer?Buffer is a solution, that resist change in pH, by adding or removing H+ ions to the solution.
Maintaining a constant pH is necessary to complete many reactions.
In blood, bicarbonates maintain the pH of the body.
[tex]CH_3COOH\; and\; CH_3COONa[/tex] have approx the nearest pH, so they can be used to make a buffer.
Thus, the correct options are [tex]CH_3COOH\; and\; CH_3COONa[/tex]
Learn more about buffer
https://brainly.com/question/24188850
- Rachel performed an investigation to study the thermal conductivity of four different materials. She started with four identically shaped rods—each made of a different material. Then, she placed one end of each rod into a pot of boiling water, which was at 100°C.
- After five minutes, Rachel measured the temperatures of the ends of the rods that were sticking up out of the pot to see whether they got hot. Her results are shown below.
Thermal Conductivity Investigation
Material Temperature of End of Rod After 5 Minutes
Material 1 41°C
Material 2 53°C
Material 3 98°C
Material 4 59°C
- Rachel knows that one of the materials is copper and that copper conducts thermal energy very well. Which of the materials is most likely copper?
A.
material 1
B.
material 3
C.
material 4
D.
material 2
Answer:
I will have the maths book
Answer:98
Explanation:
what is one property of skim milk indicating that it is a colloidal dispersion?
Answer:
it's dairy
Explanation
Which of the following is a conductor?
a) Glass
b) Wood
c) Gold
d) Oil
the answer is gold cause oil wood and glass are electrical insulators
What lives in the arctic tundra biome? Choose all that apply.
Use this website to answer the question: https://thewildclassroom.com/biomes/artictundra-2/
Question 6 options:
caribou
reptiles
amphibians
lots of insects
muskox
reindeer
Answer: Animals found in the Arctic tundra include herbivorous mammals (lemmings, voles, caribou, arctic hares, and squirrels), carnivorous mammals (arctic foxes, wolves, and polar bears), fish (cod, flatfish, salmon, and trout), insects (mosquitoes, flies, moths, grasshoppers, and blackflies), and birds (ravens, snow buntings
The lives in Artic tundra biome is caribou.
What is arctic tundra biome?Artic tundra biome is the northernmost biome, which covers the land of the arctics with the ice caps.
Climate of this Artic tundra biome is almost cold means the temperature in winter season of this region is about -34 degree celsius. In this region small animals like Norway lemmings as well as large animals like caribou are present which have high amount of fat to rescue from the cold.
Hence, option (a) is correct.
To know more about Artic tundra biome, visit the below link:
https://brainly.com/question/16056049
Potassium iodide, KI, is used as an expectorant. How many grams are in 0.300 mole of potassium iodide?
Answer: 49.8 g
Explanation: molar mass M(KI) = 39.1+ 126.9 = 166 g/mol
Mass m= n·M= 0.3 mol· 166 g/mol
Which describes bonding electrons in a polar covalent bond?
electrons that are not shared equally
electrons that are shared in diatomic molecules
electrons that are shared equally
Answer:
I think the third one
Explanation:
i think
Answer:
electrons that are NOT shared equally
Explanation:
How do chemists count the number of representative particles in a substance?
Reactants for a certain reaction are combined in a solution. Which solution
would have the most successful collisions and so enable the reaction to
proceed quickly?
A. A solution at low concentration and low temperature
B. A solution at high concentration and low temperature
O C. A solution at high concentration and high temperature
D. A solution at low concentration and high temperature
The correct answer is solution B!
Which substance is soluble in water?
Calculate the pH of a 0.10 M NH4Cl solution.
Answer:
Answer: pH = 2.72
Explanation:
Calculate the pH of 0.010 M HNO2 solution. The K, for HNO2 is 4.6 x 104
What is most likely oxidation state of aluminum (AI)?
What is true about a car with constant velocity?
A. It has a zero acceleration
B.It has a changing direction
C.postive acceleration
D. Negative acceleration
Answer:
Explanation:
c it’s see it
A gas goes from 1L at 273 K to 2 L when heated. What is the new temp?
Answer:
Given : Diatomic molecule at 273K
'q' absorbed = positive = +100Cal = 100 x 4.184J = 418.4J
'W' done by system = negative = -209J
By first law of thermodynamics;
ΔU = q + W = 418.4 + (-209) = 209.4J
We know for diatomic molecule Cv=25R and CvΔT=ΔU
CvΔT=209.4
25RΔT=209.4
ΔT=5R209.4×2
And, Heat exchange=Cm×ΔT
where; Cm is molar heat capacity
Cm=ΔTHeat Exchange
substituting values for Heat Exchange = 418.4 and ΔT=5R209.4×2
Cm=5R
What is mass times acceleration equal to?
Answer:
Mass (kg) × Acceleration (m/s²) = Force (N)
If a compressed air cylinder for scuba diving contains 6.0 L of gas at 18°C and 200 atm pressure, what volume does the gas occupy at 1.0 atm and 25°C?
Answer:
[tex]V_2=1228.9L[/tex]
Explanation:
Hello there!
In this case, given the pressure, temperature and volume of the gas, we notice that we need the combined ideal gas as shown below:
[tex]\frac{P_2V_2}{T_2} =\frac{P_1V_1}{T_1}[/tex]
Thus, solving for the final volume, V2, we would obtain:
[tex]V_2=\frac{P_1V_1T_2}{T_1P_2}[/tex]
Now, we plug in the data and make sure the temperature must be in Kelvins to obtain:
[tex]V_2=\frac{200atm*6.0L*(25+273)K}{(18+273.15)K(1.0atm)}\\\\V_2=1228.9L[/tex]
Best regards!
2Na(s) + Cl2(g) - 2NaCl(s) + 822 kj
Answer:
Is there any other part to this question? If not I'm pretty sure the answer is 205.5 kJ
Explanation:
Answer:
822 kJ; 411 kJ/mol.
Explanation:
A chemist measures the enthalpy change during the following reaction: ()()()Use this information to complete the table below. Round each of your answers to the nearest kJ/mol. 1. ()()()Solution: given reaction is 2Na + Cl2 --> 2NaCl delta H = -822 KJ 1) 1/2Na + 1/4Cl2 --> 1/2NaCl divide the coficiant of given.
A student prepared a stock solution by dissolving 20.0 g of NaOH in enough water to make 150. mL of solution. She then took 15.0 mL of the stock solution and diluted it with enough water to make 65.0 mL of a final solution. What is the concentration of NaOH for the final solution
Answer:
[tex]0.769\ \text{M}[/tex]
Explanation:
Mass of stock solution = 20 g
Molar mass of NaOH = 40 g/mol
Volume of stock solution = 0.150 mL
[tex]M_2[/tex] = Concentration of NaOH for the final solution
[tex]V_1[/tex] = Amount of stock solution taken = 15 mL
[tex]V_2[/tex] = Total volume of solution = 65 mL
Molarity is given by
[tex]M_1=\dfrac{\text{Mass}}{\text{Molar mass}\times \text{Volume}}\\\Rightarrow M_1=\dfrac{20}{40\times 0.15}\\\Rightarrow M_1=\dfrac{10}{3}[/tex]
We have the relation
[tex]M_1V_1=M_2V_2\\\Rightarrow M_2=\dfrac{M_1V_1}{V_2}\\\Rightarrow M_2=\dfrac{\dfrac{10}{3}\times 15}{65}\\\Rightarrow M_2=0.769\ \text{M}[/tex]
The concentration of NaOH for the final solution is [tex]0.769\ \text{M}[/tex].
#7 which of the following decreases the rate of solubility of solid molecules in a solution?
Answer:
7. Option D
Explanation:
Solubility increases with the increase in temperature of the solution. It is so because the increase in temperature leads to increase in kinetic energy which then breaks the solute particles held together by intermolecular attractions.
Hence, option D is correct
29. Which is the electron configuration of an atom
in the excited state?
(1) 1s 2s²2p2
(2) 1s 2s22p'
(3) 1s 2s22p5352
(4) 1s²2s²2p%35'
Which property increases as you move down a column in the periodic table?
A) atomic size
B) ionization energy
C) nonmetallic character
D) none of the above (all increase as you move down a column).
Answer:
A) atomic size
Explanation:
A voltaic cell is assembled by using two 30-mL beakers. In one beaker, Ag metal is used as the electrode with 10 mL of 1 M AgNO3. In the other beaker, Zn metal is used as the electrode with 10 mL of 1 M ZnSO4. The beakers are connected with a salt bridge and the measured cell potential, Eocell, is 1.50 V. The Zn electrode is negative (anode). Which reaction takes place at the Zn electrode
Answer:
Reaction that takes place at the Zn electrode is oxidation:
Zn ⇄ Zn²⁺ + 2e⁻
Explanation:
This excersise explains the structure of a typical battery, that is useful to study electrochemistry.
AgNO₃ → Ag⁺ + NO₃
ZnSO₄ → Zn²⁺ + SO₄⁻²
Generally batteries contains 2 electrodes, where we have 2 conductive metallic. Batteries work to obtain electricity from a chemistry reaction which is always a redox type. One electrode releases electrons while the other catch them. Electrons travel from the anode to cathode, so in the anode, the e⁻ are released.
Reaction that takes place at the Zn electrode is oxidation:
Zn ⇄ Zn²⁺ + 2e⁻
Oxidation state is increased, electrons are free to go to cathode, where the other element decreases the oxidation state:
Ag⁺ + e⁻ ⇄ Ag
In the middle of the battery, the salt bridge (generally KCl) contributes the redox with more charges. Cl⁻ for the anode and K⁺ for the cathode.
Note that the same amount of electrons travel from anode to cathode, because in this example, Ag gained 1 mol and Zn released 2 moles.
The scheme for the battery is:
⁻ Zn(s) / Zn²⁺ (aq) // Ag⁺ (aq) / Ag (s) ⁺
1 M 1 M
Where the first place represents the anode, // represents the salt bridge and then, the cathode. Below, we write the molar concentration of each salt.
.) Neon and HF have approximately the same molecular masses. a.)Explain why the boiling points of Neon and HF differ b.)Compare the change in the boiling points of Ne, Ar, Kr, and Xe with the change of the boiling points of HF, HCl, HBr, and HI, and explain the difference between the changes with the increasing atomic or molecular mass.
Answer:
See explanation
Explanation:
a) The magnitude of intermolecular forces in compounds affects the boiling points of the compound. Neon has London dispersion forces as the only intermolecular forces operating in the substance while HF has dipole dipole interaction and strong hydrogen bonds operating in the molecule hence HF exhibits a much higher boiling point than Ne though they have similar molecular masses.
b) The boiling points of the halogen halides are much higher than that of the noble gases because the halogen halides have much higher molecular masses and stronger intermolecular forces between molecules compared to the noble gases.
Also, the change in boiling point of the hydrogen halides is much more marked(decreases rapidly) due to decrease in the magnitude of hydrogen bonding from HF to HI. The boiling point of the noble gases increases rapidly down the group as the molecular mass of the gases increases.
Help me! Who ever gets to answer and has the best answer gets brainliest (very easy!)
Answer:
Fires --> These consume fuel and convert chemical energy stored in that fuel into thermal light and sound energy.
Decay -->The breakdown of dead plants and animals releases thermal energy.
Earth --> Thermal energy comes from deep inside and it is called geothermal energy.
What is the hydronium ion concentration of a solution whose pH is 4.12?
a. 5.1 x 10–6 M
b. 7.6 x 10–5 M
c. 6.4 x 10–5 M
d. 4.4 x 10–8 M
what is an optical property
Answer:
The optical properties of a material define how it interacts with light. The optical properties of matter are studied in optical physics, a subfield of optics. Wiki.pedia
Explanation:
how many grams of silver chloride are produced from 15.0 g of silver nitrate
Answer:
4.2 g
Explanation:
For each of the environments below: (1) identify your system and surroundings and (2) predict whether it would be endothermic or exothermic.a.Wood burningSystem:Surroundings:Enthalpy Change:b.Water freezingSystem:Surroundings:Enthalpy Change:c.Sweat evaporatingSystem:Surroundings:Enthalpy Change:d.Chemical hand-warmerSystem:Surroundings:Enthalpy Change:
Answer:
A) Wood burning
system : Wood.
surroundings : atmosphere
Enthalpy : Exothermic
B) Water Freezing system
System : Refrigerator
surroundings : water in the refrigerator
enthalpy change : Endothermic
C) Sweat evaporating
System : Human being
surroundings : Air nearby
Enthalpy change : exothermic
D) Chemical Hand-warmer
system : Hand warmer pack
Surroundings : human palms
Enthalpy Change : Exothermic
Explanation:
A) Wood burning
system : Wood
surroundings : atmosphere
Enthalpy : Exothermic
This system give away energy to its surroundings hence its enthalpy change is exothermic
B) Water Freezing system
System : Refrigerator
surroundings : water in the refrigerator
enthalpy change : Endothermic
The system absorbs heat from what is put inside(surroundings ) of it hence this is na endothermic system
C) Sweat evaporating
System : Human being
surroundings : Air nearby
Enthalpy change : exothermic
This is an exothermic reaction ( enthalpy change ) because the system gives out heat to the surrounding
D) Chemical Hand-warmer
system : Hand warmer pack
Surroundings : human palms
Enthalpy Change : Exothermic
There is movement of heat from the system to the surrounding hence it is an exothermic reaction
.....plllzzz heeelp me fast??
Answer:
Explanation:
It is 11
Theses are all the points
I have left
Would you rather Go to jail for the rest of your life or go to prison for the rest of you life?
Answer:
I honestly don't know but I hope you get more points! ;D
Explanation: