Answer:
a group of electrochemical cells that can be recharged
explain the chemical reaction
A chemical reaction is when reactants are converted into another substance (also called products). Their reaction rearranges the constituent atoms of the reactants to give different substances as products.
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in heating a kettle of water on an electric stove, 3.34×10^3 J of thermal energy was provided by the element of the stove. yet, the water in the kettle gained only 5.95×10^2 J of thermal energy. determine the percent efficiency of the electrical element in heating the kettle of water
Answer:
The percentage efficiency of the electrical element is approximately 82.186%
Explanation:
The given parameters are;
The thermal energy provided by the stove element, [tex]H_{supplied}[/tex] = 3.34 × 10³ J
The amount thermal energy gained by the kettle, [tex]H_{absorbed}[/tex] = 5.95 × 10² J
The percentage efficiency of the electrical element in heating the kettle of water, η%, is given as follows;
[tex]\eta \% = \dfrac{H_{supplied} - H_{absorbed} }{H_{supplied}} \times 100[/tex]
Therefore, we get;
[tex]\eta \% = \dfrac{3.34 \times 10^3 - 5.95 \times 10^2}{3.34 \times 10^3} \times 100 = \dfrac{549}{668} \times 100 \approx 82.186 \%[/tex]
The percentage efficiency of the electrical element, η% ≈ 82.186%.
An ice cube melting is a physical change b. An ice cube melting is a chemical change c. Paper burning is a physical change d. Paper burning is a chemical change e. Bubbles forming when soda pop is poured into a glass is a physical change f. Bubbles forming when soda pop is poured into a glass is a chemical change g. Hard-boiling an egg is a physical change h. Hard-boiling an egg is a chemical change
Answer:
An ice cube melting is a physical change because melting doesn't change the composition of the element. Paper burning is a chemical change because combustion occurs. Bubbles forming in a soda does involve chemical changes. Hard-boiling an egg is a chemical change because the egg's composition changed.
Which of the following could be classified as a molecular element?
Question 1 options:
krypton
lithium
nitrogen
calcium
All four are classified as molecular elements.
Answer:
calcium is the correct answer to the question
A gas has a pressure of 450 mmHg at 100 degrees Celsius. What will its new pressure be when the temperature rises 200 degrees Celsius
Answer:
P2 = 900 mmHg.
Explanation:
Given the following data;
Initial pressure = 450 mmHg
Initial temperature = 100°C
Final temperature = 200°C
To find the final pressure, we would use Gay Lussac's law;
Gay Lussac states that when the volume of an ideal gas is kept constant, the pressure of the gas is directly proportional to the absolute temperature of the gas.
Mathematically, Gay Lussac's law is given by;
[tex] PT = K[/tex]
[tex] \frac{P1}{T1} = \frac{P2}{T2}[/tex]
Making P2 as the subject formula, we have;
[tex] P_{2}= \frac{P1}{T1} * T_{2}[/tex]
[tex] P_{2}= \frac{450}{100} * 200 [/tex]
[tex] P_{2}= 4.5 * 200 [/tex]
Final pressure, P2 = 900 mmHg.
Fe-54 = 5.845%
Fe-56 = 91.754%
Fe-58 = 2.119%
Calculate the average atomic mass/given their percent abundance
Answer:
[tex]\boxed {\boxed {\sf 55.76756 \ amu}}[/tex]
Explanation:
The average atomic mass is the sum of the product of the given masses and their abundances. We have to complete two steps for each isotope, then add all the products together.
Fe-54
Convert the percent abundance to a decimal by dividing by 100.
5.845/100= 0.05845Multiply the abundance as a decimal by the mass number. This is the number after the element in the isotope symbol (54 amu).
0.005845 * 54=3.1563 amuFe-56
Convert the percent to a decimal.
91.754/100=0.91754Multiply the decimal by the mass number (56 amu).
0.91754 * 56= 51.38224 amuFe-58
Convert the percent to a decimal.
2.119/100=0.02119Multiply by the mass number (58 amu).
0.02119 * 58 = 1.22902 amuAverage Atomic Mass
Add all the products together to find the average atomic mass.
3.1563 amu + 51.38224 amu + 1.22902 amu =55.76756 amuThe average atomic mass given the percent abundance is 55.7656 atomic mass units.
Ecstasy is one example of which of the following?
Depressants
Narcotics
O Club drugs
Stimulants
Answer:
Narcotics
I think ans is
Explanation:
tropicaia
Ecstasy, also known as MDMA, is used recreationally, so it can be called a club drug. However, it is illegal in the US, so it would be considered a narcotic as well. The effects it has are also of the stimulant variety, so they would fall under that category as well. It is definitely not a depressant.
heyy guys, so basically i need help with stoichiometric calculation I will give you 100 points just to answer all of these answers accurately with working out (ps ill mark you brainliest x), thanks. PLEASE HELPPP. I'm desperate x
3. What masses of ethanol and ethanoic acid would need to be reacted together to give 1 g of ethyl ethanoate?
C^2H^5OH + CH^3CO^2 H → CH^3CO^2C^2H^5 + H^2O
4. What mass of iron(III) oxide would need to be reduced to produce 100 tonnes of iron in a blast furnace?
Fe^2^O^3 + CO → Fe + CO^2
5. What mass of silver nitrate as a solution in water would need to be added to 5 g of sodium chloride to
ensure complete precipitation of the chloride?
AgNO^3(aq) + NaCl (aq) → AgCl (s) + NaNO^3(aq)
6. Copper(II) oxide reacts with sulphuric acid to produce copper(II) sulphate. If this is allowed to crystallise the formula of the crystals is CuSO 4 .5H 2 O. What mass of copper oxide would be needed to produce 100 g of crystals?
CuO + H^2O + H^2SO^4 = CuSO^4 .5H^2O
7. In the following reactions calculate the mass of precipitate formed from 20 g of the metal salt in each case.
a. ZnSO^4 (aq) + 2NaOH → Zn(OH)^2(s) + Na^2SO^4(aq)
b. Al^2 (SO^4 ) 3(aq) + 6NaOH → 2Al(OH)^3(s) + 3Na^2SO^4(aq)
c. MgSO^4(aq) + 2NaOH → Mg(OH)^2(s) + Na^2^SO^4(aq)
Answer:
3. The mass of ethanol required is approximately 0.522869 g
The mass of ethanoic acid required is approximately 0.68156 g
4. The mass of iron (III) oxide required is approximately 285.952.189.095 tonnes
5. The mass of silver nitrate required is approximately 14.53 grams
6. The mass of copper oxide that would be needed is approximately 31.86 grams
7. a. The mass of the precipitate, Zn(OH)₂ formed is approximately 49.712 grams
b. The mass of the precipitate, Al(OH)₃ formed is approximately 13 grams
c. The mass of the precipitate, Mg(OH)₂, formed is approximately 14.579925 grams
Explanation:
3. The 1 mole of ethanol and 1 mole of ethanoic acid combines to form 1 mole of ethyl ethanoate
The number of moles of ethyl ethanoate in 1 gram of ethyl ethanoate, n = 1 g/(88.11 g/mol) = 1/88.11 moles
∴ The number of moles of ethanol = 1/88.11 moles
The number of moles of ethanoic acid = 1/88.11 moles
The mass of ethanol = (46.07 g/mol) × 1/88.11 moles = 0.522869 g
The mass of ethanoic acid in the reaction = 60.052 g/mol × 1/88.11 moles ≈ 0.68156 g
4. 1 mole of iron(III) oxide reacts with 1 mole of CO₂ to produce 1 mole of iron
The number of moles in 100 tonnes of iron= 100000000/55.845 = 1790670.60614 moles
The mass of iron (III) oxide required = 159.69 × 1790670.60614 = 285952189.095 g ≈ 285.952.189.095 tonnes
5. The number of moles of NaCl in 5 grams of NaCl = 5 g/58.44 g/mol = 0.0855578371 moles
The mass of silver nitrate required, m = 169.87 g/mol × 0.0855578371 moles ≈ 14.53 grams
6. The number of moles of CuSO₄·5H₂O in 100 g of CuSO₄·5H₂O = 100 g/(249.69 g/mol) ≈ 0.4005 moles
The mass of copper oxide required, m = 79.545 g/mol × 0.4005 moles ≈ 31.86 grams
7. a. The number of moles of NaOH in the reaction = 20 g/(39.997 g/mol) ≈ 0.5 moles
2 moles of NaOH produces 1 mole of Zn(OH)₂
0.5 moles of NaOH will produce 0.5 mole of Zn(OH)₂
The mass of 0.5 mole of Zn(OH)₂ = 0.5 mole × 99.424 g/mol = 49.712 grams
The mass of the precipitate, Zn(OH)₂ formed = 49.712 grams
b. 6 moles of NaOH produces 2 moles Al(OH)₃
20 g, or 0.5 mole of NaOH will produce (1/6) mole of Al(OH)₃
The mass of the precipitate, Al(OH)₃ formed, m = 78 g/mol×(1/6) moles = 13 grams
c. 2 moles of NaOH produces 1 mole of Mg(OH)₂, therefore;
20 g or 0.5 moles of NaOH formed (1/4) mole of Mg(OH)₂
The mass of the precipitate, Mg(OH)₂, formed, m = 58.3197 g/mol × (1/4) moles = 14.579925 grams
Answer:
Explanation:
i will show in details how 2 do the 1st Q n u can do the rest by following the way how it is done
3. given C^2H^5OH + CH^3CO^2H → CH^3CO^2C^2H^5 + H^2O
molar ratio of ethanol, ethanoic acid and ethyl ethanoate is 1 : 1 : 1
so mass = no. of moles * molecular mass
for same no. of moles, mass / molecular mass is the same
molecular mass of CH^3CO^2C^2H^5 = 12+1*3+12+16*2+12*2+5*1 = 88
molecular mass of C^2H^5OH = 12*2+1*5+16+1 = 46
molecular mass of CH^3CO^2H = 12+1*3+12+16*2+1 = 60
1 g of ethyl ethanoate = 1/88 mole
it requires 1/88*46 = 0.5227 g of ethanol; and
1/88*60 = 0.6818 g of ethanoic acid
to react together to form 1 g of ethyl ethanoate
Which best describes a swimming pool?
A.
It is a solute.
• B.
It IS
solvent.
C.
It is solution.
D.
It is a reactant.
•
E.
It is a product.
Answer:
Swimming pool is an example of solution
Explanation:
It has water (solvent) and dissolve ion (solute)
Answer:
it is a solution
Explanation:
the combining of (water and Cl and other pool chemicals) make it a solution.
Cotton plant is mainly harvested at flowering stage true false
4. What is the mass of 0.468 moles of C6H12O6?
PLEASEEE HELP ASAPP
Answer:
84.324 gram
Explanation:
mass = no of moles * molar mass
mass = 0.468 * 180.18 = 84.324 grams
explain about brownian movement in your own word
Answer:
Brownian moment means zig-Zag motion of particals Randomly anywhere in the free space or in fluids
What is the equilibrium constant of pure water at 25°C
this symbol (g) in a chemical formula indicates that
Answer:
indicates that the substance is in a gaseous state
Crystals of sodium chloride were prepared by the following method.
1 25.0 cm3
of dilute hydrochloric acid was accurately measured into a conical flask.
2 Aqueous sodium hydroxide was added until the solution was neutral. The volume of
sodium hydroxide added was measured.
3 The solution was evaporated and the crystals washed with approximately 15 cm3
of water.
Which row shows the pieces of apparatus used to measure the 25.0 cm3
of hydrochloric acid, the
volume of aqueous sodium hydroxide and the 15 cm3
of water?
Answer: the answer is C
IF U MIGHT NEED AN EXPLANATION FEEL FREE TO COMMENT
The laboratory equipment like the burette, pipette, and measuring cylinders are used in process of titration process. The solution of NaOH is added by the burette. Thus, option C is correct.
What is titration?Titration has been the analytical technique that uses the known and measured quantity of the solution to estimate the volume of another solution with an unknown volume and known molar concentration.
The laboratory equipment like burette, pipette, and measuring cylinders are used in measuring the volume in the titration process. The burette is filled with sodium hydroxide to measure its quantity.
The pipette is used to transfer the volume of the solution that is known (hydrochloric acid) and the measuring cylinder is used to measure the liquid (water) that is used in chemistry experiments.
Therefore, option C. pipette, burette, and measuring cylinder are the apparatus used in the titration process.
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Answer the two questions for 15pts
Answer:
For 1: 6.68 g of nitrogen dioxide will contain [tex]8.73\times 10^{22}[/tex] number of molecules
For 2: The given amount of nitrogen dioxide molecules has a mass of 41.31 g.
Explanation:
According to the mole concept:
1 mole of a compound contains [tex]6.022\times 10^{23}[/tex] number of molecules
The number of moles is defined as the ratio of the mass of a substance to its molar mass. The equation used is:
[tex]\text{Number of moles}=\frac{\text{Given mass}}{\text{Molar mass}}[/tex] ......(1)
For 1:We are given:
Mass of nitrogen dioxide = 6.68 g
Molar mass of nitrogen dioxide = 46 g/mol
Putting values in equation 1, we get:
[tex]\text{Moles of nitrogen dioxide}=\frac{6.68g}{46g/mol}=0.145mol[/tex]
Using above concept:
If 1 mole of a compound contains [tex]6.022\times 10^{23}[/tex] number of molecules
So, 0.145 moles of nitrogen dioxide will contain = [tex](0.145\times 6.022\times 10^{23})=8.73\times 10^{22}[/tex] number of molecules
Hence, 6.68 g of nitrogen dioxide will contain [tex]8.73\times 10^{22}[/tex] number of molecules
For 2:We are given:
Molecules of nitrogen dioxide = [tex]5.41\times 10^{22}[/tex] molecules
Using the above concept:
If [tex]6.022\times 10^{23}[/tex] number of molecules are present in 1 mole of a compound
So, [tex]5.41\times 10^{22}[/tex] number of molecules will be present in = [tex]\frac{1mol}{6.022\times 10^{23}}\times 5.41\times 10^{22}=0.898[/tex] moles of nitrogen dioxide
We know, molar mass of nitrogen dioxide = 46 g/mol
Using equation 1:
[tex]0.898mol=\frac{\text{Mass of nitrogen dioxide}}{46g/mol}\\\\\text{Mass of nitrogen dioxide}=0.898mol\times 46g/mol=41.31g[/tex]
Hence, the given amount of nitrogen dioxide molecules has a mass of 41.31 g.
True or false
The atomic number of an element is always more than the mass number of that elemenT
A gas is put into a cosed container.
The container and the gas inside it are heated.
What will happen to the pressure inside the container?
Answer:
When gases in containers are heated, their molecules increase in average speed. This means that they exert a greater force when they collide with the container walls, and also collide with the walls more frequently. The gas is therefore under greater pressure when its temperature is higher.
Which statement is the best description of a chemical bond
Answer:
What are your given options? I can't answer unless I know those :)
Explanation:
Anthracite coal d) is the most abundant grade of coal e) is very soft and burns at high temperatures a) causes the most air pollution c) is very hard and burns cleanly b) has the highest sulfur content
Answer: The correct option is C ( is very hard and burns cleanly).
Explanation:
COAL is a form of rock that is made up of mostly carbon amongst other elements which includes sulphur, nitrogen, hydrogen and oxygen. There are different types of coal which include:
--> anthracite ( 90% carbon)
--> bituminous coal ( 70-90% carbon)
--> lignite ( 60- 70% carbon) and
--> peat (60 % carbon).
Anthracite is the type of coal that contains the highest carbon content ( 90% carbon). This makes it very hard and is often a times referred to as HARD COAL. Anthracite is a higher quality coal for domestic and open fire heating. This is because it contains less impurities than other type of coal and thereby making it to BURN CLEANLY avoiding atmospheric pollution.
The reaction below shows how the potential energy changes during a phase
change. What does the red arrow show?
Potential Energy
Reaction Progress
A. The change in enthalpy is positive, and the reaction is
endothermic.
B. The change in enthalpy is negative, and the reaction is exothermic.
C. The activation energy is negative, and the reaction is exothermic.
D. The activation energy is positive, and the reaction is endothermic.
Answer:
the red arrow shows that the change in enthalpy is positive
From the energy diagram, it is clear that, the enthalpy of the reaction is positive and it is an endothermic reaction.
What is an endothermic reaction ?An endothermic reaction is a chemical reaction that absorbs heat from its surroundings, resulting in a decrease in temperature of the surroundings. In other words, energy is taken in by the reaction from the environment.
During an endothermic reaction, the reactants absorb energy in the form of heat, light, or electricity to break the bonds between their atoms and form new bonds to create products.
The amount of energy absorbed by the reactants is greater than the energy released by the products. This energy difference is usually expressed as the enthalpy change (∆H) of the reaction, which is positive for endothermic reactions.
Here, the energy of products is higher than that of reactants and hence option A is correct.
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A train is accelerating at a rate of 2 m/s. If its intital velocity is 20 m/s,what is its veolcity after 30 seconds
Answer:
80 m/s.
Explanation:
NOTE: This is a physics question. However, the solution to the question given below:
From the question given above, the following data were obtained:
Acceleration (a) = 2 m/s²
Initial velocity (u) = 20 m/s
Time (t) = 30 s
Final velocity (v) =?
The final velocity of the train can be obtained as shown below:
v = u + at
v = 20 + (2 × 30)
v = 20 + 60
v = 80 m/s
Therefore, the final velocity of train is 80 m/s.
what is average velocity with formula?
Answer:
total displacement \time
Explanation:
How many oxygen (O) atoms would a carbon (C) atom need to bond with to form a stable compound?
A.3
B.4
C.1
D.2
What are the values of the solute amount in moles and the solution volume in liters.
Answer:
0.250L of solution. 0.250 moles of solute.
Explanation:
As you can see in the image, there is a beaker with an amount of solution. 1/2L are 500mL and each line of the beaker represents 100mL. That means the volume of the solution is approximately 250mL = 0.250L
Molarity is an unit of concentration defined as the moles of solute per liter of solution. A solution that is 1.000M contains 1.000 moles of solute per liter of solution.
As the volume of the solution is 0.250L, the moles are:
0.250L * (1.000mol/L) = 0.250 moles of solute
Which experiment led to the idea that atoms contain a nucleus?
Answer:
Rutherford's gold foil experiment showed that the atom is mostly empty space with a tiny, dense, positively-charged nucleus. Based on these results, Rutherford proposed the nuclear model of the atom.
Explanation:
1:Which one of the following solutions shows no current flow in an electrolytic cell?
A: water solution of table salt
B: molten sodium chloride
C: hydrochloric acid solution
D: sugar solution
Answer: Sugar solution shows no current flow in an electrolytic cell.
Explanation:
Electric current is the flow of ions or charged species from one point to another.
A solution that does not contain any ions is not able to conduct electric current.
Water solution of table salt (NaCl) contains sodium and chlorine ions. So, an electric current can pass through it.Molten sodium chloride also contains sodium and chlorine ions. Hence, an electric current can pass through it.Hydrochloric acid solution contains [tex]H^{+}[/tex] and [tex]Cl^{-}[/tex] ions. So, an electric current can pass through it.Sugar solution does not contain ions as sugar only dissolves in water but do not dissociate into ions. Hence, current cannot flow through sugar solution.Thus,, we can conclude that sugar solution shows no current flow in an electrolytic cell.
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Formula of xenon trioxide = XeO3
Relative atomic mass: Xe = 131.29, O = 16
Question 1
number of moles = mass / molar mass
n of XeO3 = 9.07 / 131.29 + 3(16)
= 0.05059 mol
number of moles = number of particle / Alvagadro's constant
0.05059 = number of molecule / 6.02 x 10²³
number of molecules = 3.046 x 10²²
Question 2
number of moles = number of particle / Alvagadro's constant
number of moles = 3.22 x 10²² / 6.02 x 10²³
number of moles = 0.05349 mol
number of moles = mass / molar mass
0.05349 = mass / 131.29 + 3(16)
mass = 9.590g
One problem with using pesticides to control insects on crops is that the insects can develop resistance to the chemicals. How is this similar to the overuse of antibiotics?
Answer:
Explanation:
Overuse of antibiotics leads to bacteria's resistance against our drugs. This is increasing at an alarming rate and the reason is that overuse of antibiotics kills bacteria that lack the "resistance" gene or gene that can help them survive the antibiotics (similar is the case for insects that die to insecticides). But, some bacteria can have random mutations in their gene that can help them survive the antibiotic (similar is the case for some insects that can survive the insecticide), thus the surviving bacteria give rise to next generation of bacteria that are resistant to the given antibiotic (similar to how insects that survive the insecticide give birth to new insects that are resistant to insecticide too). Soon, every generation adds new antibiotic resistant bacteria (or new insecticide resistant insects in the case of insects) which is dangerous for all of life on this planet. Therefore, both are similar in the sense that new generations of these organisms will be resistant to our weapons against them.
gases does not have definite shapes and volume ? (give a scientific reason for the following)
Answer:
Gases do not have a definite shape or volume because the molecules in gases are very loosely packed, they have large intermolecular spaces and hence they move around. ... The particles of solid are closely packed and occupy less space while particles of gases are loosely packed and occupy the complete space available.
Explanation:
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