Answer:
2.28 × 10^-3 mol/L
Explanation:
The equation for the equilibrium is
CN^- + H2O ⇌ HCN + OH^-
Ka = 4.9 × 10^-10
KaKb = Kw
4.9 × 10^-10 Kb = 1.00 × 10^-14
Kb = (1.00 × 10^-14)/(4.9 × 10^-10) = 2.05 × 10^-5
Now, we can set up an ICE table
CN^- + H2O ⇌ HCN + OH^-
I/(mol/L) 0.255 0 0
C/(mol/L) -x +x +x
E/(mol/L) 0.255 - x x x
Ka = x^2/(0.255 - x) = 2.05 × 10^-5
Check for negligibility
0.255/(2.05 × 10^-5) = 12 000 > 400. ∴ x ≪ 0.255
x^2 = 0.255(2.05 × 10^-5) = 5.20 × 10^-6
x = sqrt(5.20 × 10^-6) = 2.28 × 10^-3
[OH^-] = x mol/L = 2.28 × 10^-3 mol/L
Which is a fossil fuel?
A.nuclear
B.Biomass
C.geothermal
D.coal
Answer:
Coal
Explanation:
Coal is composed of the remains of dead animals and plants, being pressed down over the course of thousands of years.
(Also can I please have Brainliest? I need it to level up)
Answer:
coal
Explanation:
a fossil fuel is a general term for buried combustible geologic deposits of organic materials formed from decayed plants and animals. hope this helps i took physical science.
• identify early ideas about evolution
Answer:
There are two ideas about evolution.
1.) Religious
2.) Scientific
In religion, people believe that we were created through god.
In the scientific, people believe that we were created from apes and that throughout the time we became humans.
Explanation:
Naturalists began to focus on the variability of species; the emergence of paleontology with the concept of extinction further undermined static views of nature. In the early 19th century Jean-Baptiste Lamarck (1744–1829) proposed his theory of the transmutation of species, the first fully formed theory of evolution.
In classical Latin, though, evolution had first denoted the unrolling of a scroll, and by the early 17th century, the English word evolution was often applied to 'the process of unrolling, opening out, or revealing'. It is this aspect of its application which may have been behind Darwin's reluctance to use the term.
Rate or Reaction Past Exam Questions 2
10 Fatimah investigates the reaction between sodium hydrogencar
acid.
reaction between sodium hydrogencarbonate and dilute hydrocrc
She always adds 0.5g of sodium hydrogencarbonate to 20 cm of dilute hydrochia
She measures the time it takes for the reaction mixture to stop bubbling.
This is called the reaction time.
She does five different experiments.
She keeps the temperature the same.
Each experiment uses a different concentration of acid.
Look at a graph of her results.
1004
60F
reaction time
in seconds
0.5
1.5
2
.0
2.5
1.0
concentration in mol/dms
Fatimah concludes that as the concentration of acid increases, the rate of reaction increases.
Explain, with a reason, whether the results support Fatimah's conclusion.
Use the reacting particle model to explain Fatimah's results.
The quality of written communication will be assessed in your answer to this question.
The experiment results support Fatimah's conclusion that higher acid concentration increases the reaction rate, based on the reacting particle model and the kinetic molecular theory.
Explanation:Based on the description of the experiment, Fatimah observed that as the concentration of acid increased, the reaction time decreased, indicating that the rate of reaction increased. This can be explained by the reacting particle model, which suggests that with a higher concentration of acid, there are more acid particles in a given volume. This increases the likelihood of effective collisions between acid particles and sodium hydrogencarbonate particles, thereby increasing the rate of reaction.
The relationship between the concentration of reactants and the rate of reaction is explained in kinetic molecular theory. In the case of sodium hydrogencarbonate reacting with hydrochloric acid, producing bubbles of carbon dioxide, we would see a shorter reaction time with higher concentrations of acid. This is due to more frequent and effective collisions, which is consistent with the results as shown in Fatimah's graph. Calculating reaction rate involves the change in concentration of reactants or products over time, which can be reflected in the dynamics of the experiment she conducted.
Answer ASAP 50 pts
What sources of error may have contributed to the percent yield not being 100 percent? Think about things that may have led to inaccurate measurements or where mass of the product could have been lost if this experiment was conducted in a physical laboratory.
Percent yield is the ratio between actual and theoretical yield multiplied by 100%. The higher the actual yield the higher is the percent yield. In the percent yield there is always a limiting reagent that creates the difference between what is obtained and what is calculated. Percent yield can never exceed 100% if that happens it means that there was some error in the theoretical yield calculation.
why is concentrated sulphuric acid is weak acid
Answer:
Sulfuric acid is a strong acid in any state
Explanation:
You may be thinking if the definition that a weak acid produces relatively few ions in aqueous solution,
If you have 100 % sulfuric acid, there is no water, so the definition does not apply.
Commercial sulfuric acid contains about 2 % water. The sulfuric acid in that small amount of water consists of about 99 % HSO₄⁻ and 1 % SO₄²⁻. The acid is almost completely ionized.
Sulfuric acid is a strong acid.
The Galilean moons are satellites of which planet? Jupiter Mars Saturn Uranus
Answer:
Jupiter
Explanation:
The Galilean moons of Jupiter are Io, Europa, Ganymede, and Callisto.
Answer:
Jupiter
Explanation:
The Galilean moons are the four largest moons of Jupiter, first found by Galileo Galilei in either December of 1609 or January of 1610. He recognized them are satellites in March of 1610.
What does the letter R symbolize in a structural formula, such as RCOOH?
Answer:
R means there's a number of carbon in the chain.
Explanation:
For example RCOOH means that after x number of carbon, the chain ends with COOH.
Answer:
The correct answer is "a radical formed by carbons".
Explanation:
Carboxylic acids are a group of compounds characterized by a functional group called the carboxyl group. In a structural formula of a carboxylic acid, such as RCOOH, R symbolizes the existence of a radical formed by a certain amount of carbons attached to the functional group called the carboxyl group (COOH).
Have a nice day!
PLEASE.
Where are nonmetals located in the periodic table?
along the upper right side
along the bottom
along the upper left side
in the middle
Answer:
Along the upper right side
How many grams of CaCl2
are needed to make 344.9
g of a solution that is 32.0
% (m/m) CaCl2
in water? Note that mass is not technically the same thing as weight, but % (m/m) has the same meaning as % (w/w).
grams CaCl2=
g
How many grams of water are needed to make this solution?
grams H2O=
Answer:
[tex]\boxed{\text{110.4 g of CaCl$_{2 }$ and 234.5 g of water}}[/tex]
Explanation:
1. Mass of CaCl₂
[tex]\text{Let m = mass of CaCl}_{2}\\\\\begin{array}{rcl}\text{Mass percent} & = & \dfrac{\text{Mass of CaCl}_{2}}{\text{Total mass}} \times 100 \%\\\\32.0 \% & = & \dfrac{m}{\text{344.9 g}} \times 100 \% \\\\\text{32.0 $\times$ 344.9 g} & = & 100 m\\\\m & = &\dfrac{\text{32.0 $\times$ 344.9 g}}{100}\\\\ & = &\textbf{110.4 g}\\\end{array}\\\text{You need $\boxed{\textbf{110.4 g}}$ of calcium chloride}[/tex]
2. Mass of water
[tex]\text{Let m = mass of water}\\\begin{array}{rcl}\\\text{Mass of water + mass of CaCl}_{2} & = & \text{Mass of solution}\\m + 110.4 & = & 344.9\\m & = &\mathbf{234.5}\\\end{array}\\\text{The mass of water needed is $\boxed{\textbf{234.5 g}}$}[/tex]
Which statement is the best description of a chemical bond?
A. A chemical bond connects 2 different molecules.
B. A chemical bond holds atoms together.
c. A chemical bond turns molecules into atoms.
D. A chemical bond identifies atoms in a molecule.
Answer:
B. is the correct answer
A chemical bond holds atoms together,is the statement that description of a chemical bond.
What is meant by chemical bond?A chemical bond is what holds atoms together in molecules. Bonds arise from the electrostatic forces between positively charged atomic nuclei and negatively charged electrons (the positions of which in space are determined by quantum mechanics).A chemical bond holds atoms together,is the statement that description of a chemical bond.
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What does this equation, 2 C(s) + O 2(g) ® 2 CO(g), tell us?
A) the number of atoms of each kind in reactants and products is the same
B) carbon monoxide (CO) is a product
C) two atoms of carbon undergo reaction
D) all of these
Answer:
D. All of these.
Explanation:
For an equation to be balanced the number of atoms of each kind in the reactants and the products should be the same.
Then from this equation, CO is a product.
Last, two carbon atoms undergo reaction with the oxygen molecule for complete reaction to occur. Each atom combines with one oxygen atom.
Answer:
D) All of these
Explanation:
[tex]2 C(s) + O_2 (g) > 2 CO(g)[/tex]
Reactant side (Left side) Element Product side (Right side)
2 C 2
2 O 2
Balanced!!!
Balancing is making the number of atoms of each element same on both the sides (reactant and product side).
To find the number of atoms of each element we multiply coefficient × subscript
For example [tex]5 Ca_1 Cl_2[/tex] contains
5 × 1 = 5 ,Ca atoms and
5 × 2 = 10, Cl atoms
If there is a bracket in the chemical formula
For example [tex]3Ca_3 (P_1 O_4 )_2[/tex] we multiply coefficient × subscript × number outside the bracket.......... to find the number of atoms (Please note: 3 is the coefficient, and if there is no number given then 1 will be the coefficient )
So
3 × 3 = 9 , Ca atoms
3 × 1 × 2 = 6, P atoms
3 × 4 × 2 = 24, O atoms are present.
What is the study of matter called?
O
A. Chemistry
O
B. Philosophy
O
O
C. Biology
D. Physics
Hello There!
The science of matter is called chemistry. Chemistry is the science of matter and its changes that occur. Everything in our universe is made up of matter and it has to have mass and take up space to be considered this.
Assume you add 5 g of Nacl to a beaker and add water until the volume of the solution reaches 4 L. Calculate the concentration of salt in water in g/L and mol/L.
Answer:
1.25 g/L.
0.0214 mol/L.
Explanation:
Concentration in g/L = 5/4
= 1.25 g/L (answer).
As for mol / L we need to know the molar mass of salt.
It is 22.99 + 35.45 = 58.44.
So in mol/L it is 1.25 / 58.44
= 0.0214 mol/L.
Please help me! I think the answer to this is C because gas produced from liquid has the greatest release in entropy, right? And C is the only option producing gas. Please help me out! Is C the right answer or which one is?
The systems that shows the greatest increase in entropy is -
a.2H2 + O2®2H2O
b.NaCl ®Na+1 + Cl-1
c.2H2O ®2H2 + O2
d.AgCl3®Ag+3 + 3Cl-1
Answer:
c. 2H₂O → 2H₂ + O₂
Explanation:
Entropy is the state of randomness or disorderliness of the particles of a system. The more random and disorderly a system is, the more its entropy. When the physical state of matter changes, there is a considerable change in the entropy of such a system.
The increasing order of entropy is as listed below:
Solid < liquid < gas
Gases have the highest randomness in all states of matter.
From the equation of the reaction in option C, we see that water is going into the gaseous phase. The products of the reaction are hydrogen and oxygen gases. This is an increase in entropy.
Reaction B and D produced ions which are in aqeous solutions. They move from originally solid sate to a liquid phase.
Reaction A takes gases and turns them into water. This is a decrease in entropy.
is when two atoms combine to form a larger atom,
The process of _
releasing energy.
Nuclear fusion is a process where light atomic nuclei merge to form a heavier nucleus, releasing energy due to the mass difference being converted into energy. This reaction powers stars and has potential applications in generating clean energy on Earth.
The process being described is known as nuclear fusion. It occurs when two light atomic nuclei combine to form a larger, heavier nucleus, typically releasing a significant amount of energy. This process explains why fusion is considered a potential source of almost inexhaustible clean energy. In stars, such as our Sun, fusion is the energy-producing process, where hydrogen nuclei fuse under intense pressure and temperature to form helium, outputting immense energy in the process.
In terms of mass, the total mass of the resulting heavier nucleus is slightly less than the sum of the original nuclei. This difference in mass, according to Einstein's equation E = mc2, is converted into energy, which is radiated away. The ability to control nuclear fusion on Earth is a goal of many research programs, as it promises a less hazardous and more abundant alternative to current nuclear fission power plants.
An atom of boron has an atomic number of 5 and an atomic mass of 11. The atom contains
5 protons, 6 electrons, and 5 neutrons.
11 protons, 11 electrons, and 5 neutrons.
5 protons, 5 electrons, and 6 neutrons.
11 protons, 6 electrons, and 6 neutrons.
Answer:
5 protons, 5 electrons, and 6 neutrons
An atom of boron has 5 protons, 5 electrons, and 6 neutrons. This composition aligns with its atomic number of 5 and an atomic mass of 11. Therefore, the correct option is the one with 5 protons, 5 electrons, and 6 neutrons.
To determine the composition of a boron atom, we need to understand the concepts of atomic number and atomic mass. Boron has an atomic number of 5, which means it has 5 protons. The atomic mass of boron is approximately 11, which is the sum of the number of protons and neutrons.
Given these details, the correct configuration of a boron atom with an atomic number of 5 and an atomic mass of 11 is:
5 protons5 electrons6 neutronsThus, an atom of boron has 5 protons, 5 electrons, and 6 neutrons. This corresponds to the configuration that meets both the atomic number and atomic mass criteria as mentioned earlier.
Give the location of the elements found in the periodic table which have the same number valence electrons.
A. All members in group VIII only
B. All numbers within any group
C. All numbers within any period
D. All the nonmetals
Answer:
B - all numbers within any group (vertical column)
Explanation:
https://en.wikipedia.org/wiki/Valence_electron
Answer:
B - all numbers within any group
Explanation:
Determine the number of moles. 2.4x10^24 atoms of Fe
why does matter change from one phase to another
Answer:
the state of matter depends on its temperature and pressure. example, at constant pressure of 1atm (atmospheric pressure), water at 100 degrees Celsius is vapor, and at different phases at different temperature. Note that's at pressure other than 1atm, water will not boil (be vaporized) at 100 degrees Celsius, it could be lesser or higher(depending on whether pressure is increased or decreased).
Therefore, the state of mater changes with respect to temperature and pressure action on it.
How many grams of PbBr2 will precipitate when excess CrBr; solution is added to 60.0 mL of 0.551 M Pb(NO3)2 solution?
3Pb(NO3)2(aq) + 2CrBr3(aq) –>3PbBrz(s) + 2Cr(NO3)(aq)
Answer:
5.48 g
Explanation:
M: 367.01
3Pb(NO3)2(aq) + 2CrBr3(aq) → 3PbBr2(s) + 2Cr(NO3)3(aq)
1. Moles of Pb(NO3)2
n = 30.0 mL × (0.551 mmol/1 mL) = 16.53 mmol Pb(NO3)2
2. Moles of PbBr2
n = 16.53 mmol Pb(NO3)2 × (3 mmol PbBr/3 mol Pb(NO3)2)
= 16.53 mmol PbBr2
(3) Mass of PbBr2 formed
m = 16.53 mmol × (367.01 mg/1 mol) = 6067 mg
(4) Mass of PbBr2 in solution
PbBr2 is slightly soluble, so a significant amount will remain in solution.
Its solubility is 973 mg/100 mL.
Mass of dissolved PbBr2 = 60.0 mL × 973 mg/100 mL = 584 mg
(5) Mass of precipitate
Mass of precipitate = mass of PbBr2 formed - mass of PbBr2 in solution
m = 6067 mg - 584 mg = 5480 mg = 5.48 g
The mass of precipitate is 5.48 g.
The mass of PbBr2 precipitate produced is 12.1 g.
The equation of the reaction is;
3Pb(NO3)2(aq) + 2CrBr3(aq) –>3PbBr2(s) + 2Cr(NO3)3(aq)
Number of moles of Pb(NO3)2 = 60.0/1000 L × 0.551 M = 0.0331 moles
From the information in the question, we already know that Pb(NO3)2 is the limiting reactant and CrBr3 is the reactant in excess.
From the equation of the reaction;
3 moles of Pb(NO3) yields 3 moles of PbBr2
0.0331 moles of Pb(NO3) yields 0.0331 moles × 3 moles/3 moles
= 0.0331 moles of PbBr2
Mass of PbBr2 = number of moles × molar mass
Mass of PbBr2 = 0.0331 moles × 367 g/mol= 12.1 g
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what is h20????????????????????
Answer:
H2O is the chemical formula for water or in simple language its is water
Explanation:
Water, one of the most vital elements for life on Earth, has the chemical formula [tex]H_20[/tex]. It is made up of one oxygen atom and two hydrogen atoms joined together covalently.
Due to its polar nature, water can establish hydrogen bonds with other molecules, giving it special features including high surface tension, cohesiveness, and thermal stability. It serves as a solvent, a medium for metabolic reactions, and a mechanism for controlling temperature, all of which are essential for diverse biological activities. Water is also essential to the functioning of Earth's ecosystems since it erodes the land and supports a variety of aquatic life. Water is essential for supporting all forms of life because of its quantity and adaptability.
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why is the structure of a molecule important to its function
Answer:
It determines how biological molecules recognize and respond to one another with specificity.
Explanation:
A molecule has a characteristic size and shape. The precise shape of a molecule is usually very important to its function in the living cell. Molecular shape is crucial in biology because it determines how biological molecules recognize and respond to one another with specificity.
Answer:
the structure of a molecule affects how it interacts with other molecules
Explanation:
I took the test
is mercury a solution
Answer:
No.
Explanation:
Mercury is not a solution. It is a detonator.
Which cohesive forces are the strongest in water?
A.) London dispersion forces
B.) dipole interactions
C.) hydrogen bonding interactions.
D.) All intermolecular forces in water are equally strong.
how many moles of gas Does it take to occupy 520 mL at a pressure of 400 torr and a temperature of 340 k
A.73.6 moles
B. 0.0098 moles
C.0.980 moles
D. 0.0735 moles
Final answer:
To find how many moles of gas occupy a given volume under certain conditions, we use the ideal gas law PV = nRT with proper unit conversions. Upon calculation with the conditions provided (520 mL at 400 torr and 340 K), the result is approximately 0.0098 moles, which is option B.
Explanation:
To determine how many moles of gas occupy 520 mL at a pressure of 400 torr and a temperature of 340 K, we use the ideal gas law equation PV = nRT. To use this equation, we must first convert the volume of the gas from mL to L (since R, the gas constant, is given in liters), and the pressure from torr to atm because R is also defined with pressure in atmosphere. 1 atm = 760 torr, so 400 torr is equal to 400 torr / 760 torr/atm = 0.5263 atm. The volume is 520 mL, which is 0.520 L. The value of R (the gas constant) is 0.0821 L atm / (K mol).
Now we can plug values into the ideal gas law:
PV = nRT
(0.5263 atm) × (0.520 L) = n × (0.0821 L atm / (K mol)) × (340 K)
After calculation, we find:
(0.5263 atm × 0.520 L) / (0.0821 L atm / (K mol) × 340 K) = n
n ≈ 0.0098 moles
Therefore, the answer is (B) 0.0098 moles.
Which of these statements best describes the formula unit for a compound made from Mg and Cl?
It is MgCl2 because the total negative charge on Cl is one.
It is Mg2Cl because the total negative charge on Mg is one.
It is MgCl2 because the total positive charge on Mg is two.
It is Mg2Cl because the total positive charge on Mg is two.
WILL MARK BRAINLIEST
Answer:
It is MgCl₂ because the total positive charge on Mg is two
Explanation:
The bond between the atoms that makes up the formula unit of the compound is an ionic bond. This bond involves the transfer of electrons between atoms.
Mg is in the second group on the period on the periodic table. It has two valence electrons and would readily lose it to have a stable atomic configuration like those of noble gases. This leaves magnesium with a net positive charge of 2. Each chlorine atom gains one electron to achieve their own octet.
The formula unit of a substance composed of magnesium (Mg) and chlorine (Cl) is [tex]MgCl_2.[/tex] Therefore, the correct option are C and D.
This is due to the fact that while chlorine has a negative charge of -1, magnesium has a positive charge of +2. Two chloride ions combine with one magnesium ion to equalize the charges and provide electrical neutrality.
The two chlorine ions combine to provide a total negative charge of -2 because each chlorine ion adds a charge of -1. The negative charge of the chlorine ions is balanced by the +2 charge of the magnesium ions. As a result, the molecule formed by the combination of one magnesium ion and two chlorine ions is represented by the formula unit [tex]MgCl_2[/tex].
Therefore, the correct option are C and D.
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Which of the following types of energy does an object have because of its motion?
Chemical energy
Gravitational energy
Kinetic energy
Potential energy
Answer: Kinetic energy
Explanation:
Chemical energy is the energy stored in the bonds of molecules.
Gravitational energy is the potential energy held by an object because of its higher position compared to a lower position.
Kinetic energy is the energy possessed by a body by virtue of its motion.
Potential energy is the energy possessed by a body by virtue of its position.
Thus kinetic energy is the energy associated with an object because of its motion.
In free fall, all objects fall with the same acceleration.
O
A. True
O
B. False
Answer:
A. True
Explanation:
Objects that are said to be undergoing free fall, are not encountering a significant force of air resistance; they are falling under the sole influence of gravity. Under such conditions, all objects will fall with the same rate of acceleration, regardless of their mass
Answer:
true
Explanation:
weight and shape does not matte in a perfect world unfortunately they are effected in our world where there is friction and air resistance
A 50°C solution has a pH of 3.30. At this temperature, Kw = 5.48 x 10 9. What is the pOH of the solution?
Answer:
9.93
Explanation:
Your value for Kw is incorrect. The correct value is 5.48 × 10^-14.
pH + pOH = pKw
3.30 + pOH = -log(5.84 × 10^-14) = 13.23
pOH = 13.23 - 3.30 = 9.93
The pOH of the solution is 9.93.
The pOH of the solution is 10 .
Given that, the pH of the solution is 3.30, we also know that;
pH = - log[H^+]
Hence;
[H^+] = Antilog (-3.3)
[H^+] = 5.0 × 10^-4 M
But;
Kw = [H^+] [OH^-]
[OH^-] = Kw/[H^+]
The accurate value of Kw is 5.48 × 10^-14 not 5.48 x 10 9
[OH^-] = 5.48 x 10^-14/ 5.0 × 10^-4
[OH^-] = 1.1 x 10^-10 M
pOH = - log[1.1 x 10^-10 M]
pOH = 10
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Consider the following unbalanced redox reaction:
Cr2O72- (aq) + NO2 (aq) – Cr3+ (aq) + NO3(aq)
What is the oxidizing agent in the reaction?
The oxidizing agent in the reaction Cr2O72- (aq) + NO2 (aq) – Cr3+ (aq) + NO3 (aq) is Cr2O72-, as it is reduced, meaning it accepts electrons, going from a chromium oxidation state of +6 to +3.
Explanation:In a redox reaction, the oxidizing agent is the substance that is reduced, meaning it gains electrons. In the unbalanced reaction: Cr2O72- (aq) + NO2 (aq) – Cr3+ (aq) + NO3(aq), the Cr2O72- ions are reduced to Cr3+ ions.
This is determined through the observation of the oxidation states of the substances before and after the reaction. The oxidation state of chromium in Cr2O72- is +6, while it is +3 in Cr3+. This reduction in oxidation state indicates that Cr2O72- accepted electrons, meaning it is the oxidizing agent in this reaction.
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