The statement that describes a question that can guide the design of a scientific investigation could be about the necessity of a controlled variable. The correct answer is A.
What is a controlled variable?It is a variable whose values are controlled by the researcher during the course of experimental investigations.
When designing an experiment, it is necessary to identify the different variables that would be involved for a successful investigation.
Variables can be independent, dependent, controlled, or constant. Identifying the necessary variables will help in designing the experiment.
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An exergonic reaction __________ free energy, and an endergonic reaction __________ free energy.
Atom is a smallest particle of an element which have all the chemical properties of that element.What is the origin of Atom.
Answer:
ORIGIN OF ATOM.Sometimes peoples like to say that atom is like a cell in living things,is it true?comment below,letss goo!!
Explanation:
A greek philosopher known as Democritus was the first to consider the idea that matter is made up of small particles ,about 400BC.
Since there was no experimental evidence to support his idea,it was not accepted.
About 2000 years later an English man called John Dalton revived the discussion.He used experimental evidence to support his idea to convince people that matter is made up of particles called atoms.It accepted!.
An English man called John Dalton revived the discussion.He used experimental evidence to support his idea to convince people that matter is made up of particles called atoms.It was accepted ,he conclude the following theories:
Matter is made up of tiny particles called atom which cannot be splitted into simpler substancesAtom cannot be created nor destroyedA 25.0 g sample of metal at
16.0 °C is warmed to 22.1 °C
by 259 ] of energy.
What is the change in temperature
for the metal?
Record your answer to the tenths place.
The change in temperature of the metal is 6.1°C. Details about change in temperature can be found below.
How to calculate change in temperature?The change in temperature of a substance can be calculated by subtracting the initial temperature of the substance from the final temperature.
According to this question, a 25.0 g sample of metal at 16.0 °C is warmed to 22.1 °C by 259J of energy.
This means that the change in temperature of the metal can be calculated as:
∆T = 22.1°C - 16°C
∆T = 6.1°C
Therefore, the change in temperature of the metal is 6.1°C.
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Answer: 6.1°C.
Explanation: just for some extra verification, the answer is indeed 6.1°C. Hope this helps and have a great day!
The chemical formula for a emerald is BeAl2(SiO3)6.
An emerald can be described as
Emerald can be described as a transparent, green coloured gem stone made up of mineral beryl together with trace amount of chromium or sometimes vanadium having chemical formula as [tex]Be_3Al_2(SiO_3)_6[/tex] .
Through time, the emerald has been known as a symbol of truth and love.
In ancient Greece and Rome, emerald was said to be the gemstone of the goddess Venus, purveyor of love and hope.
On the other side of the world, emeralds were revered by the Incas and believed by the Egyptians to be a source of eternal life.
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Which industrial methods of preparing alcohol are more economical? Explain.
The industrial methods of preparing alcohol that is more economical is fermentation.
What is fermentation?Fermentation is defined as the industrial method by which starch is converted to ethyl alcohol by using some specific enzymes and microorganisms known as yeast
It is an economical method because the raw material which is starch is readily available.
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An ice cube absorbs 353 cal of
energy from its surroundings.
How many joules of energy is
this?
Answer:
1482.6 J
Explanation:
353 cal * 4.2 J / 1 cal = 1482.6 J
An ice cube absorbs 353 cal of energy from its surroundings. Number of joules of energy is 1482.6 Joules.
What is Energy?The ability to do work is called as energy. Work done is product of force and displacement. Energy is of different types as sound energy, kinetic energy, potential energy, electrical energy, light energy etc.
Law of conservation of energy states that energy can neither be created nor destroyed, but it can be transferred from one form to another.
Molecules can move so they show kinetic energy, molecules can be there at many positions so they can show potential energy, molecules can vibrate so they can show sound energy but molecules can only absorb light hence they can't have light energy.
1 calorie of energy has 4.2 Joules.
Given, 353 Calories of Energy
Hence, 353 Calories of Energy has 1482.6 Joules.
Therefore, An ice cube absorbs 353 cal of energy from its surroundings. Number of joules of energy is 1482.6 Joules.
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2Na+S→Na2S
What is the total number of moles of S that react when 4.0 moles of Na were completely consumed?
Answer:
2.0 moles S
Explanation:
To find the number of moles of S, you need to convert the moles Na to moles S via the mole-to-mole ratio. This ratio is represented by the coefficients in the balanced equation. Because you wish to find moles S, you want to put this number in the numerator. Because you want to eliminate the moles Na, this number should be in the denominator.
2 Na + 1 S ---> Na₂S
4.0 moles Na 1 mole S
---------------------- x --------------------- = 2.0 moles S
2 moles Na
Ammonia, NH3(g), can be used as a substitute for fossil fuels in some internal combustion
engines. The reaction between ammonia and oxygen in an engine is represented by
the unbalanced equation below.
NH3(g) + O₂(g) →→ N₂(g) + H₂O(g) + energy
6. Balance the equation in the space below for the reaction of ammonia and oxygen, using the
smallest whole-number coefficients.
Answer:
4 NH₃ (g) + 3 O₂ (g) ----> 2 N₂ (g) + 6 H₂O (g) + energy
Explanation:
The unbalanced equation:
NH₃ (g) + O₂ (g) ----> N₂ (g) + H₂O (g) + energy
Reactants: 1 nitrogen, 3 hydrogen, 2 oxygen
Products: 2 nitrogen, 2 hydrogen, 1 oxygen
The sort-of balanced equation
2 NH₃ (g) + 1/2 O₂ (g) ----> N₂ (g) + 3 H₂O (g) + energy
I first started by balancing the nitrogens. This then lead me to balance the hydrogens. When I went to balance the oxygens, only a 1/2 coefficient would work. However, 1/2 coefficients are technically incorrect. To get rid of this coefficient, you need to multiply each coefficient by 2.
The balanced equation:
4 NH₃ (g) + 3 O₂ (g) ----> 2 N₂ (g) + 6 H₂O (g) + energy
Reactants: 4 nitrogen, 12 hydrogen, 6 oxygen
Products: 4 nitrogen, 12 hydrogen, 6 oxygen
Now, all of the elements are equal on both sides and there are no 1/2 coefficients. These are the smallest whole-number coefficients because some of the numbers cannot be further simplified (3).
Two samples contain sulfur and
oxygen in the amounts shown in the
data table. What is the mass percent
of sulfur in compound B?
Sample Mass S (g) Mass 0 (g)
A
32.0
48.0
B
30.0
30.0
Answer:
Sample A=40 Sample B=50
Explanation:
32+48=80
32/80x100=40
The 100 is to convert it to a percentage
___________________________
Sample B
same thing
30+30=60
30/60x100=50
The mass percent of sulfur in compound B is 50 %
What is mass percent?Mass percent is defined as a way of expressing a concentration or describing the component in a particular mixture.
It can also be defined as a mass of a element or solute divided by the mass of compound or solvent.
Mass percent of sulfur of sample A
= 32 + 48 = 80
= 32 / 80 x 100
= 40 %
Mass percent of sulfur of sample B
= 30 + 30 = 60
= 30 / 60 X 100
= 50 %
Thus, the mass percent of sulfur in compound B is 50 %
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5.00g of an unknown metal we know has a +2 charge (M^+2) is reacted with an excess of hydrochloric acid (HCl(aq)). The product is dried and weighs 11.35 grams. What is the formula and name of the product formed?
the formula: MCl₂
name of the product formed: chloride salt + hydrogen
There are 4.78 g of dry LICIO4 and
2.43 g H₂O in the sample.
Step 2: Determine the moles of water and anhydrous compound.
Li = 6.94 g/mol, Cl = 35.45 g/mol,
H = 1.01 g/mol, O = 16.00 g/mol
How many moles of LICIO4 are present?
[?] mol LICIO4
Answer:
The number of moles of H₂O is 0.135 mol.
The number of moles of LiClO₄ is 0.0449 mol.
Explanation:
Mole is an important standard unit used for the measurement of large quantities of atoms, molecules, or other particles. One mole is equal to 6.022×10²³ units.
The number of moles of a substance is calculated by:
[tex]\frac{mass of substance}{molecular weight of substance}[/tex]
To find the number of moles of H₂O:
Mass of H₂O in the sample = 2.43g
The molecular weight of H₂O = 18.02g
Number of moles = [tex]\frac{2.43}{18.02}[/tex] = 0.135 mol.
To find the number of moles of LiClO₄:
Mass of LiClO₄ given = 4.78g
The molecular weight of LiClO₄ = 106.39g
Number of moles = [tex]\frac{4.78}{106.39}[/tex] = 0.0449 mol.
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Answer:
0.0449
Explanation:
No probelm
WILL GIVE BRAINLIEST
The table shows the number of reactants and products present during two separate chemical reaction
Which of the following statements correctly identifies the decomposition reaction and describes a substance involved?
Chemical reaction A, because the reactant is a compound
Chemical reaction B, because the product is a compound
Chemical reaction A, because the reactant is an element
Chemical reaction B, because the product is an element
Answer:
Chemical reaction A, because the reactant is a compound
Explanation:
In a decomposition reaction, a compound is broken down into its components, so the number of products is greater than the number of reactants
Chemical reaction A, because the reactant is a compound is a statements correctly identifies the decomposition reaction and describes a substance involved.
What is chemical reaction?When atoms establish or break chemical bonds, chemical processes take place. Reactants are the substances that begin a chemical reaction, while products are the compounds that are created as a result of the reaction.
Although a chemical reaction is not always a "one-way street," as we'll examine further in the next section, an arrow is drawn between the reactants and products to denote the direction of the reaction.
Our equation must have them in it in order for there to be an equal number of atoms of each element on both sides of the equation.
Therefore, Chemical reaction A, because the reactant is a compound is a statements correctly identifies the decomposition reaction and describes a substance involved.
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pls solve
question attached as image
Answer:
a) formula for citric acid is - C6 H8 o7
b) lime water turns opaque after adding co2 due to the formation of calcium carbonate.
c) reaction 3 is displacement reaction where a high reactive metal displace a less reactive from its salt solution.
d) reaction 1) is combination reaction where two reactant combines to give a single product whereas reaction 2) is decomposition reaction where a single reactant splits into more that 1 products.
in chemistry what is Faraday's law
Answer:
Faraday’s – First Law of Electrolysis
It is one of the primary laws of electrolysis. It states, during electrolysis, the amount of chemical reaction which occurs at any electrode under the influence of electrical energy is proportional to the quantity of electricity passed through the electrolyte.
Faraday’s – Second Law of Electrolysis
Faraday’s second law of electrolysis states that if the same amount of electricity is passed through different electrolytes, the masses of ions deposited at the electrodes are directly proportional to their chemical equivalents.
From these laws of electrolysis, we can deduce that the amount of electricity needed for oxidation-reduction depends on the stoichiometry of the electrode reaction.
The product of an electrolytic reaction depends on the nature of the material being electrolysed and the type of electrodes used. In the case of an inert electrode such as platinum or gold, the electrode does not participate in the chemical reaction and acts only as a source or sink for electrons. While, in the case of a reactive electrode, the electrode participates in the reaction.
Hence, different products are obtained for electrolysis in the case of reactive and inert electrodes. Oxidizing and reducing species present in the electrolytic cell and their standard electrode potential too, affect the products of electrolysis.
FAQs
1. What’s a Faraday?
Ans: The Faraday is an electric charge volume unit without measurements, equal to approximately 6.02 x 10 23 electric charge carriers.
2. Why is Faraday’s law important?
A shifting magnetic flux creates an electric field, according to Faraday’s law. Faraday’s law is particularly important since it addresses the connection of the E-field and the B-field and understands that this connection necessitates flux fluctuation over time.
3. How does electrolysis remove rust?
Ans: Electrolysis is a method of removing iron oxide by passing a small electrical charge through the rusty metal from a battery or battery charger to induce ion exchange while the device is submerged in an electrolyte solution.
4. What happens to water during electrolysis?
Ans: Water’s Electrolysis. By passing an electrical current through it, water can be decomposed. When this happens, an oxidation-reduction reaction is caused by the electrons from the electric current.
5. What is the negative electrode called in electrolysis?
Ans: Through electrolysis, the negatively charged electrode is called the cathode. The positively charged electrode is called the anode in electrolysis. Negatively charged ions are moving towards the anode.
Hope it helps!
Answer:
Faraday's law states that the absolute value or magnitude of the circulation of the electric field E around a closed loop is equal to the rate of change of the magnetic flux through the area enclosed by the loop.
Explanation:
Hope It Helps!!!
how to minimize the harmful effects of power station on our environment
Which statement illustrates the difference between a chemical reaction and a nuclear reaction?A nuclear reaction releases more energy per gram and appears to violate the law of conservation of mass.A nuclear reaction releases less energy per gram and appears to violate the law of conservation of mass.A nuclear reaction releases more energy per gram but does not appear to violate the law of conservation of mass.A nuclear reaction releases less energy per gram but does not appear to violate the law of conservation of mass.
According to the research, a nuclear reaction releases less energy per gram and appears to violate the law of conservation of mass.
What is a nuclear reaction?It is a procedure that leads to combining and modifying the nuclei of atoms and subatomic particles and appears to violate the law of conservation of mass.
Through this kind of process, the nuclei can be combined or fragmented, absorbing or releasing particles and energy according to each case.
Therefore, we can conclude that according to the research, a nuclear reaction releases less energy per gram and appears to violate the law of conservation of mass.
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increasing the airplane's speed or wing size does which of the following
a) decreases the amount of drag on the plane
b) increases the gravitational pull on the pane
c) generates more lifting force
d) creates a sonic boom
Answer:
increases the gravitional pull on tge pane
Answer:
generates more lifting on the plane
Explanation:
What is the name of CH3CH2CHMgBr(CH3)?
Answer:
Ethyl magnesium Bromide
Helpp!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
A homogenous mixture is that mixture in which the components mix with each other and its composition is uniform throughout the solution. A heterogenous mixture is that mixture in which the composition is not uniform throughout and different components are observed.
will you be my friend
Answer:
your cool
Explanation:
How many moles of sulfur are in 80 grams of sulfur?
A. 1.5 moles
B. 2.5 moles
C. 1 mole
D. 2 moles
Answer:
2.5 moles
Explanation:
Number of moles = MassMolar mass
= 80⋅g32.06⋅g⋅mol−1 = ??mol
Note that sulfur likely exists in its elemental state as S8. I am perfectly justified in treating sulfur as S. The number of sulfur atoms is the same in each case.
Scientists are trying to find out why bees are dying in large numbers. Which best describes how the scientists will try to solve the problem?
A. They will do the same experiments to obtain similar evidence.
B. They will only work with scientists who share the same opinions.
C.
They will observe the same patterns and draw the same conclusions
D.
They will approach the problem in different ways but share ideas.
Answer: D. They will approach the problem in different ways but share ideas.
If the pH of a solution is 4.7, what is the H+ concentration?
Answer:
0.000019952mol/dm3
Explanation:
pH=-log(H+)
4.7= -log(H+)
log(H+)=-4.7
(H+)=10*-4.7=0.000019952
A student was given a mixture of iron of iron fillings and sulphur. He was told to heat it and observe the compound.
(a) What is coloured formed.
(b) Write the effect of magnet on it.
(c) Write the action of carbon disulphide on it.
(d) Describe the effect of adding dilute hydrochloric acid to it. ldentify the gas and write its two properties.
The observations are as follows:
black iron sulfide is formed iron sulfide is not magnetic No reaction observed with carbon sulfidehydrogen gas is evolved What is the product of the reaction of iron fillings and sulfur when heated?When a mixture of iron fillings and sulfur are heated, black iron (ii) sulfide is formed.
Unlike iron fillings, black iron (ii) sulfide is not attracted to a magnet.
When carbon sulfide is added to it, no visible reaction is observed.
When dilute hydrochloric acid is added to it, a gas with a rotten-egg smell is evolved.
The gas is hydrogen sulfide which is a reducing agents and acidic in nature.
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PLEASE HELP FAST! How many grams of NO are formed if 8.3 g of ammonia react with 11.8 g of oxygen? The reaction is 4NH3 + 5O2 --> 4NO + 6H2O.
Options:
A. 8.85 g NO
B. 12.6 g NO
C. 14.6 g NO
D. 9.3 g NO
The mass of NO produced is 9.3 g; option D.
What mass of NO is produced from the reaction?
The mass of nitrogen (ii) oxide, NO, produced from the reaction is determined from the mole ratio of the reaction.
The mole ratio of ammonia to oxygen from the equation of the reaction is 4 : 5.
moles of oxygen = 11.8/32 = 0.368
moles of ammonia = 8.3/17 = 0.488
Oxygen is the limiting reactant.
Mass of NO produced = 0.369 * 4/5 * 30 = 9.4 g NO
In conclusion, approximately 9.3 g of NO is produced.
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Suppose that you add 26.7 g of an unknown molecular compound to 0.250 kg of benzene, which has a K f Kf of 5.12 oC/m. With the added solute, you find that there is a freezing point depression of 3.89 oC compared to pure benzene. What is the molar mass (in g/mol) of the unknown compound
From the calculation, the molar mass of the solution is 141 g/mol.
What is the molar mass?We know that;
ΔT = K m i
K = the freezing constant
m = molality of the solution
i = the Van't Hoft factor
The molality of the solution is obtained from;
m = ΔT/K i
m = 3.89/5.12 * 1
m = 0.76 m
Now;
0.76 = 26.7 /MM/0.250
0.76 = 26.7 /0.250MM
0.76 * 0.250MM = 26.7
MM= 26.7/0.76 * 0.250
MM = 141 g/mol
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calculate the number of moles in positive and negative ions in 1.75 moles of calcium fluoride quizlet
CaF₂ ⇒ Ca²⁺ + 2F⁻
1.75 1.75 3.5
Which energy source from a reservoir would provide affordable, abundant electricity for a factory? solar panels wind turbines gas generators a hydroelectric plant
The energy source from a reservoir would provide affordable, abundant electricity for a factory is a hydroelectric power plant; option D.
What is energy?Energy is the ability to do work.
Energy generating plants may either use wind, water or solar energy to produce electrical energy.
The most abundant source of energy from a reservoir is hydroelectric power plant.
Therefore, the energy source from a reservoir would provide affordable, abundant electricity for a factory is a hydroelectric power plant.
In conclusion, hydroelectric power plants are reservoirs of abundant energy supply.
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PROBLEMS
1. What is the molarity of 4 grams of NaOH dissolved in 1 liter of solution?
2. What is the molarity of 4 grams of NaOH dissolved in 0.5 liter of solution
3. What is the molarity of 4 grams of NaOH dissolved in 0.1 liter of solution
4. Which of the 3 solutions above is more concentrated and why?
Answer:
1.) 0.1 M
2.) 0.2 M
3.) 1 M
4.) Solution #3 is the most concentrated because it has the highest molarity. This solution has the largest solute to solvent ratio. The more solvent there is, the lower the concentration and molarity.
Explanation:
To find the molarity, you need to (1) convert grams NaOH to moles (via molar mass from periodic table) and then (2) calculate the molarity (via the molarity equation). All of the answers should have 1 sig fig to match the given values.
Molar Mass (NaOH): 22.99 g/mol + 16.00 g/mol + 1.008 g/mol
Molar Mass (NaOH): 39.998 g/mol
4 grams NaOH 1 mole
---------------------- x ------------------ = 0.1 moles NaOH
39.998 g
1.)
Molarity = moles / volume (L)
Molarity = (0.1 moles) / (1 L)
Molarity = 0.1 M
2.)
Molarity = moles / volume (L)
Molarity = (0.1 moles) / (0.5 L)
Molarity = 0.2 M
3.)
Molarity = moles / volume (L)
Molarity = (0.1 moles) / (0.1 L)
Molarity = 1 M
A 20.0-ml sample of glucose Iv solution has a mass of 20.6g.what is the density of the glucose
Taking into account the definition of density, the density of the glucose is 1.03 [tex]\frac{g}{mL}[/tex].
What is densityDensity is defined as the property that matter, whether solid, liquid or gas, has to compress into a given space.
In other words, density is a quantity that allows us to measure the amount of mass in a certain volume of a substance. Then, the expression for the calculation of density is the quotient between the mass of a body and the volume it occupies:
[tex]density=\frac{mass}{volume}[/tex]
From this expression it can be deduced that density is inversely proportional to volume: the smaller the volume occupied by a given mass, the higher the density.
Density of the glucoseIn this case, you know that:
Density= ?Mass= 20.6 gVolume= 20 mLReplacing in the definition of density:
[tex]density=\frac{20.6 g}{20 mL}[/tex]
Solving:
density= 1.03 [tex]\frac{g}{mL}[/tex]
In summary, the density of the glucose is 1.03 [tex]\frac{g}{mL}[/tex].
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entir
What is the striking back of
the
bunsen-
burner?
Answer:
With too little air, the gas mixture will not burn completely and will form tiny carbon particles that are heated to glowing, making the flame luminous. With too much air, the flame may burn inside the burner tube; that is, it may strike back.