B
Atomic mass = no. of proton
Atomic mass= P +N
27= 13+N
N=14
Answer:
14
Explanation:
The atomic # is how many protons it has, the mass is the total number of protons (P) and neutrons (N).
P+N=M 13+N=27
27-13=14 Neutrons= 14
Which year was DNA evidence introduced?
1908
1988
1980
1998
1988 was when it was first introduced
Final answer:
DNA evidence was first introduced in 1988 and has since revolutionized forensic science. Its discovery by Miescher in 1869 and subsequent research paved the way for its pivotal role in modern biology and criminal justice.
Explanation:
DNA evidence was first introduced in 1988. This introduction of DNA for forensic purposes marked a monumental advancement in the field of criminal investigations and legal proceedings. The science of DNA was discovered by Friedrich Miescher in 1869, and significant developments unfolded over the years, leading to our contemporary understanding of DNA as the genetic material responsible for heredity. Experiments by scientists such as Oswald Avery, Colin MacLeod, and Maclyn McCarty in the 1940s, and the discovery of the 3D-double-helix structure by James Watson and Francis Crick in 1953, set the stage for the many applications of DNA science we see today, including forensic analysis.
A gas has a mixture containing oxygen, nitrogen, & carbon dioxide has a total pressure of 32.0 kPa. If oxygen = 6.6 kPa, nitrogen = 23.0 kPa, what is the pressure of the carbon dioxide ?
Answer:
2.4 kPa.
Explanation:
According to Dalton's law: the total pressure of an ideal gas mixture is equal to the sum of the partial pressures of the gases in the mixture.
Herein;Ptotal = P of O₂ + P of N₂ + P of CO₂.
where, Ptotal is the total pressure = 32.0 kPa,
P of O₂ is partial pressure of oxygen gas = 6.6 kPa,
P of N₂ is the partial pressure of nitrogen gas = 23.0 kPa,
P of CO₂ is the partial pressure of carbon dioxide gas = ??? kPa.
∵ Ptotal = P of O₂ + P of N₂ + P of CO₂.
∴ 32.0 kPa = 6.6 kPa + 23.0 kPa + P of CO₂.
∴ P of CO₂ = 32.0 kPa - (6.6 kPa + 23.0 kPa) = 2.4 kPa.
Rhea has a balloon that contains 0.5 mole of helium. how many particles of helium are in the balloon?
Answer:
[tex]\boxed{3 \times 10^{23}}[/tex]
Explanation:
1 mol of helium contains 6.022 × 10²³ atoms
[tex]\text{Atoms of He} =\text{0.5 mol He} \times \dfrac{ 6.022 \times 10^{23} \text{ atoms He}}{\text{1 mol He}}= 3 \times 10^{23} \text{ atoms He}[/tex]
The balloon contains [tex]\boxed{3 \times 10^{23} \text{ atoms of He}}[/tex].
69.253 helium particles are in the balloon.
What is helium particles?Helium is composed of two electrons bound by the electromagnetic force to a nucleus containing two protons along with either one or two neutrons, depending on the isotope, held together by the strong force. Unlike for hydrogen, a closed-form solution to the Schrodinger equation for the helium atom has not been found.
A helium atom is an atom of the chemical element helium. Helium is composed of two electrons bound by the electromagnetic force to a nucleus containing two protons along with either one or two neutrons, depending on the isotope, held together by the strong force. Unlike for hydrogen, a closed-form solution.
Helium is the element which you can find on the upper right side of the periodic table with atomic number 2. It comes first amongst the family of the noble gases. Helium falls under inert gas since its outermost electron orbital is full with two electrons.
The answer is 69.253.
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Hello! I need help with this question asap please! ;-;
Match the following chemical reactions: A, B, C, and D are elements.
A + BC ---- AC + B Combustion
AB + BD --- AC + BD Synthesis
A + O2 - AO Combustion
AB -- A + B Single Replacement
A + B - AB Double Replacement
AC + O2 - CO2 + H2O Decomposition
Answer:
A + BC → AC + B Single Replacement
AB + CD → AC + BD Double Replacement
A + O₂ → AO Combustion
AB → A + B Decomposition
A + B → AB Synthesis
AC + O₂ → CO₂ + H₂O Combustion
Explanation:
Single replacement is a type of chemical reaction where an element reacts with a compound and takes the place of another element in that compound.So, A + BC → AC + B is an example for single replacement reaction.
Here, A replaces B in the compound BC.
Double Replacement is a type of chemical reaction where two compounds react, and the positive ions (cation) and the negative ions (anion) of the two reactants switch places, forming two new compounds or products.So, AB + CD → AC + BD is an example for double replacement reaction.
Here, A replaces C in the compound CD and B replaces D in the compound CD.
Combustion reactions always involve molecular oxygen O₂. Anytime anything burns (in the usual sense), it is a combustion reaction. Combustion reactions are almost always exothermic (i.e., they give off heat).So, A + O₂ → AO and AC + O₂ → CO₂ + H₂O are examples of combustion reactions.
Decomposition reactions is a type of chemical reaction in which a single compound breaks down into two or more elements or new compounds. These reactions often involve an energy source such as heat, light, or electricity that breaks apart the bonds of compounds.So, AB → A + B is an example for decomposition reactions.
where Ab is decomposed for A and B.
Synthesis is a type of reaction in which multiple reactants combine to form a single product. Synthesis reactions release energy in the form of heat and light, so they are exothermic.So, A + B → AB is an examples for the synthesis reactions.
Which of the following would most likely be oxidizing agents, and which would most likely be reducing agents? (Hint: Think in terms of tendencies to lose or gain electrons.) a. Cl2 b. K c. Ag+ d. Zn2+
Answers:
a) Cl₂: oxidizingb) K: reducingc) Ag⁺: oxidizingd) Zn²⁺: oxidizingExplanation:
An oxidizing agent is one that accepts electrons, being reduced, and oxidizing other atoms.A reducing atent is one that releases electrons, getting oxidized and reducing other atoms.See each choice:
a. Cl₂
Cl₂ is the diatomic molecule formed by the covalent bonding of two Cl atoms.The oxidation state of the molecule is zero (this is a rule, the oxidation state of any atom alone or bonded to other atom of the same kind is zero).Since, Cl is highly electronegative, it will mostly behave as oxidizing agent, i.e. it will accept electrons reducing itself while oxidizing other atoms.b. K
K (potassium) is an alkaline metal, which means that it has a valence electron. It is relatively easy for K to donate its electron. In this process K will oxidize itself (incrrease its oxidation state) while reduce other atoms, so this is would most likely be a reducing agent.c. Ag⁺
Since, Ag⁺ has a positive charge, it will gain stability by accepting an electron, meaning that it will get reduced, most likely being an oxidizing agent.d. Zn²⁺
Similarly to the case above, the cation Zn²⁺ would gain stability by gaining electrons, which means that it would most likely get reduced, and be an oxidizing agent.In terms of gaining and losing electrons, Cl2 and Ag+ (which gain electrons) are oxidizing agents. K, which loses an electron, is a reducing agent. Zn2+ also gaining electrons, acts also as an oxidizing agent.
Explanation:In terms of tendencies to lose or gain electrons, a substance that tends to gain electrons and acts in oxidation reactions is called an oxidizing agent. Conversely, a substance that tends to lose electrons and acts in reduction reactions is known as a reducing agent.
Looking at the substances in question: a. Cl2 tends to gain electrons and hence would act as an oxidizing agent. b. K tends to lose an electron, and thus it would be a reducing agent. The c. Ag+ ion would gain an electron to become neutrally charged Ag, making it an oxidizing agent. Lastly, d. Zn2+ can also gain electrons and become neutral, making it an oxidizing agent as well.
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A book with a weight of 12 N rests on its back cover. If the back cover measures 0.21 m by 0.28 m, how much pressure does the book exert?
A. 42 Pa
B. 57 Pa
C. 12.46 Pa
D. 204 Pa
Answer:
option D = 204 Pa
Explanation:
Given data:
Weight of book = 12 N
Area of book = 0.21 m × 0.28 m = 0.0058 m²
Pressure of book = ?
Solution:
formula
pressure = force / area
P = f/ A
now we will put the values in formula,
P = 12 N/ 0.0058 m²
P= 204 Nm⁻² ( Nm⁻²= Pa)
P = 204 Pa
The correct Answer is option (D). The pressure exerted by the book is approximately 204 Pa.
To find the pressure exerted by the book, we can use the formula for pressure:
[tex]\[ \text{Pressure} = \frac{\text{Force}}{\text{Area}} \][/tex]
First, calculate the area of the back cover:
[tex]\[ \text{Area} = \text{length} \times \text{width} \][/tex]
[tex]\[ \text{Area} = 0.21 \, \text{m} \times 0.28 \, \text{m} \][/tex]
[tex]\[ \text{Area} = 0.0588 \, \text{m}^2 \][/tex]
Now, calculate the pressure:
[tex]\[ \text{Pressure} = \frac{12 \, \text{N}}{0.0588 \, \text{m}^2} \][/tex]
[tex]\[ \text{Pressure} \approx 204.08 \, \text{Pa} \][/tex]
Rounding to the nearest whole number, the pressure exerted by the book is approximately 204 Pa.
If a given power plant released so2 gas with a volume v of 1200 m3 at a density ρ of 2.86 kg/m3 at standard pressure and temperature, how many moles n of so2 are released? the atomic weight of sulfur is 32.07 u and the atomic weight of oxygen is 16.00 u.
Answer:
[tex]\boxed{\text{52 840 mol}}[/tex]
Explanation:
Since you have the volume of the gas at STP, we can use the Ideal Gas Law to calculate the number of moles. The identity of the gas doesn't matter.
pV = nRT
n = (pV)/(RT)
Data:
p = 1 bar
V = 1200 m³ = 1.2 × 10⁶ dm³
R = 0.083 14 bar·dm³K⁻¹mol⁻¹
T = 273.15 K
Calculation:
n = (1 bar × 1.2 ×10⁶ dm³)/(0.083 14 bar·dm³K⁻¹mol⁻¹ × 273.15 K)
= 52 840 mol
The power plant releases [tex]\boxed{\text{52 840 mol of SO}_{2}}[/tex].
A solution that contains many dissolved molecules in a fixed amount of solution is called
Answer:
A solution that contains many dissolved molecules in a fixed amount of solution is called concentrated.Explanation:
Solutions are homogeneous mixtures.
A solution contains at least one solute component and one solvent component all in the same phase.
The term solubility is used to express the maximum amount of solute that can be dissolved in certain amount of solvent, and is measured at a given temperature and pressure.
You may refer to a solution as concentrated or diluted. These are kind of vague terms, in the sense that they do not express how much solute is dissolved. They just tell if there are many dissolved particles (molecules or ions), which is expressed as concentrated, or just a few particle, which is express as diluted.
Other more specific terms used to refer the amount of solute dissolved in a solution are: unsaturated solution, saturated solution, and supersaturated solution.
Unsaturated solution: the solution contains less solute than what it can have. The solution may dissolve more solute.
Saturated solution: the solution has the maximum amount of solute that it can dissolve, at certain temperature and pressure. If you add more solute to a saturated solution, it will not get dissolved (unless you change the temperature or pressure).
Supersaturated solution: a special condition where the solution contains more solute than the saturated solution, at the same temperature and pressure. This is a very unstable situation and any perturbation will make that the excess solute precipitate.
Final answer:
A solution with many dissolved molecules in a fixed amount of solvent is called a concentrated solution, characterized by its large solute-to-solvent ratio and uniform composition.
Explanation:
A solution that contains many dissolved molecules in a fixed amount of solution is called a concentrated solution. This type of solution has a relatively large amount of solute in a given amount of solvent. A solution is a homogeneous mixture of two or more pure substances. In the case of a concentrated solution, the ratio of solute to solvent is greater compared to a dilute solution, which contains a smaller amount of solute relative to the solvent.
The substance present in the larger amount is the solvent, which can dissolve other substances called solutes. During the process of dissolving, the solute particles are evenly distributed throughout the solvent creating a uniform composition. This even distribution makes the resulting solution homogeneous, meaning that the composition is the same throughout. The molarity of a solution refers to its concentration, providing a measure of the number of moles of solute per liter of solution.
You do not have a separate guest bedroom. Which of the following order of choices is correctly listed from best to worst?
master bedroom, family member’s bedroom, family room
family member’s bedroom, master bedroom, family room
family room, master bedroom, family member’s room
Answer:
master, family member, family room
The best order of choices listed from best to worst is master bedroom, family member’s bedroom, family room.
The correct order of choices from best to worst is:
Master bedroomFamily member's bedroomFamily roomThe master bedroom, being the primary bedroom, should be the best choice. The family member's bedroom is the next suitable option, and the family room is the least private space among the choices provided.
What is the molarity of a solution containing 100 moles of NaCl dissolved in 10 liters of water?
2 mol/L
10 mol/L
0.5 mol/L
5 mol/L
Answer:
10 mol/L
Explanation:
Molarity or concentration is given by the formula;
Molarity = Number of moles/Volume in Liters
In this case; number of moles = 100 and Volume = 10 L
Therefore;
Molarity = 100 moles/10 L
= 10 mol/L
The answer is 10 mol/L
The tendency of an element to react with other elements to produce compounds
Answer:
valence electrons
Explanation:
noble gases like argon or neon don't react easily with other elements because they have completely filled outer valence electron shell, but other elements react easily to try and have a noble gas structure.
Final answer:
Chemical reactivity is the propensity of an element to interact with others to form compounds, and it can be observed in reactions such as synthesis or combination reactions, where elements or compounds unite to form a new substance, following the principle that atoms are neither created nor destroyed.
Explanation:
The tendency of an element to react with other elements to produce compounds is termed reactivity, and it describes elements and compounds that are reactive and will readily react with many other substances. Reactive metals, for example, may form halide compounds with halogens or displace hydrogen from dilute acids.
When looking at chemical reactions, we must consider the starting substances that change. These are typically elements or compounds that combine in a reaction. This combination can yield a more complex compound. An example of this is a synthesis reaction, such as when sodium metal reacts with chlorine gas to form sodium chloride:
2 Na (s) + Cl2 (g) → 2 NaCl (s)
In a broader sense, chemical reactions adhere to the principle that atoms of different elements react with each other in fixed whole-number proportions to create compounds. During these reactions, atoms can separate and recombine to form new substances, but they are never created or destroyed.
Chemists have developed ways to categorize reactions to make predictions about which compounds will react and what products will be formed. Familiarity with basic types of reactions such as combination, decomposition, and displacement reactions is crucial. In the realm of combination reactions, one such reaction is the formation of carbon dioxide from the reaction of carbon monoxide with oxygen:
2CO (g) + O2 (g) → 2CO2 (g)
A train approaching a crossing changes speed from 10 m/s to 25 m/s in 240 s. How can the train's acceleration be described?
Answer:
[tex]\boxed{\text{The train is speeding up by 0.0625 m/s every second}}[/tex]
Explanation:
Acceleration (a) is the change in velocity (Δv) divided by the change in time (Δt).
[tex]a = \frac{\Delta v}{\Delta t} = \frac{v_{2} - v_{1} }{t_{2} - t_{1}} \\\\a = \frac{25 - 10}{240 - 0}=\frac{15 }{240}=\text{0.0625 m/s}^{2}\\\\\ \boxed{\textbf{The train is speeding up by 0.0625 m/s every second}}\\[/tex]
Which describes the role of energy in photosynthesis and cellular respiration?
A) Energy is needed to start photosynthesis and is a product of cellular respiration. B)Without light energy, photosynthesis and cellular respiration cannot occur. C)Energy is both a reactant and product in photosynthesis and in cellular respiration.
Answer:
A) Energy is needed to start photosynthesis and is a product of cellular respiration.
Explanation:
Answer: A). Energy is needed to start photosynthesis and is a product of cellular respiration.
Explanation:
Energy in the form of sunlight is absorbed by the plants so as to prepare their food (carbohydrates)in the process of photosynthesis.
The energy is produced in the process of cellular respiration. The cellular respiration involves the break down of glucose molecules in the food in the form of energy currencies called as ATP (Adenosine triphosphate) molecules. This form of energy is required for regulating cellular metabolism and vital functions.
Balance the following redox equation using the oxidation-number-change method. Show your work, describing each step.
HNO3 + H2S —-> S + NO + H2O
2HNO3+3H2S ——>2S+4H2O+2NO
Which system does not allow for matter or energy to be exchanged outside the system?
Isolated systems
Open system
All systems
Closed system
Isolated systems does not allow any matter or energy to be exchanged.
Isolated system does not allow for matter or energy to be exchanged outside the system.
What is isolated system ?Isolated system is a thermodynamic system that does not allow the exchange of either matter or energy outside the system.
What is Open system ?Open system is a thermodynamic system that can exchange the matter and energy with its surrounding.
What is Closed system ?A closed system is a thermodynamic system in which the exchange of energy is allowed but the exchange of matter is not allowed outside the system.
Thus, from the above conclusion we can say that Isolated system does not allow for matter or energy to be exchanged outside the system.
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When a metal is heated in a flame, the flame has a distinctive color. This information was eventually extended to the study of stars because a red shift in star color indicates stars are moving away. star color indicates the distance from the earth. the line spectra of stars indicate which elements are present. it allows the observer to determine the size of stars.
Answer:
[tex]\boxed{\text{The line spectra of stars indicate which elements are present.}}[/tex]
Explanation:
Each element has a characteristic spectrum, so analyzing the line spectra of stars tell you what elements are present.
A is wrong. The statement is true, but its not the reason why astronomers study stars.
B is wrong. The colour is a function of the star's temperature.
D is wrong. Line spectra give no information on the size of stars.
The study of metals in chemistry is called inorganic metals.
The correct option is C.
Each metal when burns give the color due to the replacement of the electron because the amount of energy is increased due to heat.
According to the question, the rest of the option is wrong because they don't have any link with the hint.
Hence, the correct option is C that is the line spectra of stars indicating which elements are present.
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The solubility of nitrogen gas at 25 degrees C and 1 atm is 6.8 x 10^(-4) mol/L. If the partial pressure of nitrogen gas in air is 0.76 atm, what is the concentration (molarity) of dissolved nitrogen?
5.2 x 10^(-4) M
1.1 x 10^(-5) M
4.9 x 10^(-4) M
3.8 x 10^(-4) M
6.8 x 10^(-4) M
Answer:
5.2 x 10⁻⁴ M.
Explanation:
The relationship between gas pressure and the concentration of dissolved gas is given by Henry’s law:P = kC
where P is the partial pressure of the gaseous solute above the solution.
k is a constant (Henry’s constant).
C is the concentration of the dissolved gas.
At two different pressures, there is two different concentrations of dissolved gases and is expressed in a relation as:P₁C₂ = P₂C₁,
P₁ = 1.0 atm, C₁ = 6.8 x 10⁻⁴ mol/L.
P₂ = 0.76 atm, C₂ = ??? mol/L.
∴ C₂ = (P₂C₁)/P₁ = (0.76 atm)(6.8 x 10⁻⁴ mol/L)/(1.0 atm) = 5.168 x 10⁻⁴ mol/L ≅ 5.2 x 10⁻⁴ M.
5.2 × 10⁻⁴ M is the concentration of dissolved nitrogen, if the partial pressure of nitrogen gas in air is 0.76 atm.
What is Henry's Law?Henry's law is proposed for the dissolved gas and it is represented as:
P = kC, where
P = partial pressure
k = henry's constant
C = concentration
And for the given question required equation for concentration is :
P₁/C₁ = P₂/C₂
P₁C₂ = P₂C₁, where
P₁ = given partial pressure of nitrogen = 1atm
C₁ = given concentration of nitrogen = 6.8×10⁻⁴ mole/L
P₂ = partial pressure of nitrogen = 0.76atm
C₂ = required concentration of nitrogen = to find?
On putting all values in the above equation we get,
1atm × C₂ = 0.76atm × 6.8×10⁻⁴ mole/L
C₂ = 5.168 x 10⁻⁴ mol/L = 5.2 × 10⁻⁴ M
Hence, option (1) is correct i.e. 5.2 × 10⁻⁴ M is the concentration of dissolved nitrogen.
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Calculate the energy released when a 28.9 gram piece of copper is cooled from its melting point of 1083 C to 25.0 c the specific heat of copper is .385 j/g c
Answer:
[tex]\boxed{\text{11.8 kJ}}[/tex]
Explanation:
The formula for the heat released is
q = mCΔT
Data:
m = 28.9 g
C = 0.385 J·°C⁻¹g⁻¹
T₁ = 1083 °C
T₂ = 25.0 °C
Calculations:
(a)Temperature change
ΔT = T₂ - T₁ = 25.0 - 1083 = -1058 °C
(b) Heat released
q = 28.9 × 0.385 × (-1058) = -11 800 J = -11.8 kJ
The negative sign shows that energy is released, so the copper has released [tex]\boxed{\textbf{11.8 kJ}}[/tex] of energy.
The energy released when a 28.9 gram piece of copper cools from 1083 °C to 25.0 °C is 11771.837 J.
The question asks to calculate the energy released when a 28.9 gram piece of copper is cooled from its melting point of 1083 °C to 25.0 °C. The specific heat of copper is given as 0.385 J/g°C. To find the energy released, we can use the formula: Energy (Q) = mass (m) × specific heat (c) × change in temperature (ΔT).
In this case, ΔT (change in temperature) = final temperature - initial temperature = 25.0 °C - 1083 °C = -1058 °C (since we are cooling down, this is a negative value, indicating heat loss). Thus, the calculation becomes Q = 28.9 g × 0.385 J/g°C × (-1058 °C).
Q = 28.9 × 0.385 × (-1058) = -11771.837 joules
The energy released by the copper as it cools down is 11771.837 (since energy release is typically considered positive, we take the absolute value).
How does the length of the day affect the seasonal temperature
The longer the day, the solar radiation is absorbed and the higher the temperature is.
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What would most likely occur if the number of cars being driven increased worldwide?
A. More coal would be burned, which would cause the amount of carbon dioxide in the atmosphere to increase.
B. More petroleum would be burned, which would cause the amount of carbon dioxide in the atmosphere to decrease.
C. More coal would be burned, which would cause the amount of carbon dioxide in the atmosphere to decrease.
D. More petroleum would be burned, which would cause the amount of carbon dioxide in the atmosphere to increase.
Answer:
D
Explanation:
Petroleum is one of the top ingredients that makes of gas. When it burns it releases exhaust made of carbon dioxide into the atmospere which has a wide range of effects.
More petroleum would be burned, which would cause the amount of carbon dioxide in the atmosphere to increase. Hence, option D is correct.
What is petroleum?Petroleum, also known as crude oil, or simply oil, is a naturally occurring yellowish-black liquid mixture of main hydrocarbons.
Petroleum is one of the top ingredients made of gas. When it burns it releases exhaust made of carbon dioxide into the atmosphere which has a wide range of effects.
Hence, option D is correct.
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What is the name of the molecule shown? Will give brainliest if its right.
Please and thank you.
A. 2,2-dimethylpropane
B. Trimethylethane
C. 3-dipropane
D. Pentane
D. Pentane. Pentane has 5 Carbon and 12 Hydrogen, like the molecule shown.
1. Household bleach (NaOCl) is really a solution of sodium hypochlorite in water. It is made by reacting chlorine gas and sodium hydroxide, as shown in the unbalanced chemical equation below: NaOH (aq) + Cl2 (g) → NaOCl (aq) + NaCl (aq) + H2 O (l) A student bubbles 83.0g of chlorine gas into an excess of aqueous sodium hydroxide. After analyzing his products, he determines that 22.0 grams of bleach are actually made. (a) What is the oxidation number of chlorine in bleach (NaOCl)? (b) Is this reaction above redox? Explain. (c) What is the percent yield of this reaction?
This is a three-part question
Answers:
a) The oxidation number of chlorine in bleach (NaOCl) is +1.b) Yes, this is a redox reactionc) The percen yield is 56.8%Explanation:
1) Part (a) What is the oxidation number of chlorine in bleach (NaOCl)?
a) Rule one: In a neutral compound the sum of the oxidation states is zero.
Since NaOCl is a neutral compound the sum of the oxidation states of Na, O and Cl is 0.
b) Rule two: since Na is an alkaline metal, its oxidation state is +1
c) Rule three: the most common state of oxygen, except in peroxides, is -2.
Then,
Na: +1O: -2Cl: xSum = +1 - 2 + x = 0 ⇒ x = 2 - 1 = 1
Conclusion: the oxidation state of NaOCl is +1.
2) Part (b) Is this reaction above redox?
In a redox reaction the oxidation states of some substances increase (get oxidized) and the oxidation states of some substances decrease (get reduced).
The reaction is represented by the chemical equation given:
NaOH (aq) + Cl₂ (g) → NaOCl (aq) + NaCl (aq) + H₂O (l)Since the chlorine gas (Cl₂) is a molecule of only chlorine atoms, its oxidation state is zero, and since chlorine is forming compounds on the right side (NaOCl and NaCl) you can immediately conclude that the oxidation state of chlorine changed, and this is a redox reaction.
In fact:
Oxidation state of Cl in Cl₂: 0Oxidation state of Cl in NaOCl: +1 (previously determined)Oxidation state of Cl in NaCl: -1 (becasue Na has oxidation state +1 and so +1 - 1 = 0).Therefore, chlorine is being oxidized (its oxidation state increases from 0 to +1) and is also being reduced (its oxidation state is reduced from 0 to -1), and this is a redox reaction.
3) Part (c) What is the percent yield of this reaction?
a) Chemical equation (given)
NaOH (aq) + Cl₂ (g) → NaOCl (aq) + NaCl (aq) + H₂O (l)b) Theoretical mole ratio:
2 mol Cl₂ (g) : 1 mol NaOCl (aq)c) Convert 83.0 g of chlorine gas to moles:
moles = mass in grams / molar massmolar mass of Cl₂(g) = 79.906 g/molmoles = 83.0 g / 79.906 g/mol = 1.039 mol Cl₂(g)d) Determine the theoretical yiedl using proportions:
x / 1.039 mol Cl₂ (g) = 1 mol NaOCl / 2 mol Cl₂ (g)⇒ x = 0.5195 mol NaOCle) Convert 0.5195 mol NaOCl to grams:
molar mass NaOCl = 22.99 g/mol + 16.00 g/mol + 35.453 g/mol = 74.443 g/molmass = number of mol × molar mass = 0.5195 mol × 74.443 g/mol = 38.67 gThat must be rounded to 3 significant figures (such as the mass of belach is given: 22.0 g)
Theoretical yiedl of NaOCl = 38.7 gf) Calculate the percent yiled:
Percent yield = (actual yield / theoretical yield) × 100Percent yield = (22.0 g / 38.7 g) × 100 = 56.8%A beaker containing 80 grams of lead(ii) nitrate, pb(no3)2, in 100 grams of water has a temperature of 30 ºc. approximately how many grams of the salt are undissolved, on the bottom of the beaker?
Answer:
14 g.
Explanation:
From the figure attached:the solubility of lead(II) nitrate, Pb(NO₃)₂, in 100 grams of water has a temperature of 30ºC is (66 g).
When beaker containing 80 grams of lead(II) nitrate, Pb(NO₃)₂, in 100 grams of water has a temperature of 30ºC.
∴ The grams of the salt are undissolved, on the bottom of the beaker are (14 g).
80 grams of lead(II) nitrate in 100 grams of water at 30ºC results in 66 grams (option c) of undissolved lead(II) nitrate.
To solve this problem, we need to know the solubility of lead(II) nitrate (Pb(NO₃)₂) in water at 30 ºC.
The solubility of Pb(NO₃)₂ in water at 30 ºC is approximately 122 g/100 mL.
Since we have 100 grams of water, we can calculate the maximum amount of Pb(NO₃)₂ that can dissolve:
Maximum soluble Pb(NO₃)₂ = 122 g/100 mL × 100 g / 1000 mL = 12.2 g
We started with 80 grams of Pb(NO₃)₂, so the amount of undissolved salt is:
Undissolved Pb(NO₃)₂ = 80 g - 12.2 g = 67.8 g ≈ 66g
Therefore, approximately 66 grams of lead(II) nitrate remain undissolved at the bottom of the beaker.
Complete Question - A beaker containing 80 grams of lead(II) nitrate, Pb(NO₃)₂, in 100 grams of water has a temperature of 30 ºC. Approximately how many grams of the salt are undissolved, on the bottom of the beaker?
a) 20 grams
b) 80 grams
c) 66 grams
d) 14 grams
How do you do this problem?
Answer:
B
Explanation:
If the temperature of the water goes up, the reaction is exothermic (heat is being given away by the equation -- more precisely the reactants of the equation). Only A and B can be true. In order for the reaction to occur, the water has to absorb the heat. It's temperature goes up. Remember that minus sign. It is almost the key fact for this question.
The question is not as hard as it looks, but that is easy for me to say.
m = 100 g
c = 4.2 J/(g * oC)
deltaT = 21 - 20 degrees = 1 degree.
Heat = 100 * 4.2 * 1
Heat = 420 J
Heat = 420 * [1 kJ/1000 J]
Heat = -0.42 kJ
B
How do you do question 1-4?
Answer:
Explanation:
4
The acid in this diagram is CH3CH2CH2-COOH. That will turn any litmus to red.
1
I'm not sure I'm reading the question correctly. I think the point is that H2 breaks up and goes on either side of the Double Bond. If that is the case, E is the correct answer. CH3CH2CH2CH3. I'm not totally sure.
2
What is happening here is the equation has progressed to kicking out one of the hydrogens and replacing it with a Br. The other Br and the kicked out Hydrogen combine to form HBr
That means (2) should be C
3
I have no idea what 3 is asking you or telling you to do
Which molecular formula is written incorrectly?
CO
CH4
Br4Si
N2
I believe your answer would be the 3rd one
Answer:
[tex]Br_{4}Si[/tex] is written incorrectly
Explanation:
In a molecular formula, the central atom in it's lewis structure is written first followed by other bonded atoms.
The least electronegative atom (except H) is the central atom in a lewis structure.
In [tex]Br_{4}Si[/tex], Si is the least electronegative atom as Br has higher electronegativity than Si. Therefore Si is the central atom in lewis structure of [tex]Br_{4}Si[/tex]. So molecular formula of [tex]Br_{4}Si[/tex] should be written as [tex]SiBr_{4}[/tex].
In all other cases, the least electronegative atom have been written first.
So, [tex]Br_{4}Si[/tex] is written incorrectly.
NEED HELP ASAP PLEASE ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
The mass of cobalt-60 in a sample decreased from 0.800g to 0.200g over a period of 10.5 years. From this information, calculate the half-life of cobalt-60.
The half-life of cobalt-60, based on the provided information and the calculation method where the sample mass decreases to a quarter over two half-lives (10.5 years), is confirmed to be 5.27 years. This example illustrates how the half-life concept helps in understanding the decay rate of radioactive isotopes.
Explanation:To calculate the half-life of cobalt-60 given that the mass of a cobalt-60 sample decreased from 0.800g to 0.200g over a period of 10.5 years, we use the concept of half-lives. The question implies that the sample underwent two half-lives for its mass to decrease to 0.200g from 0.800g.
Here's why: after one half-life, the mass would decrease to 0.400g (half of 0.800g), and after another half-life, it would decrease to 0.200g (half of 0.400g), totaling a decrease over two half-lives.
Given the provided information that the half-life of cobalt-60 is 5.27 years, this aligns perfectly with our calculation method. After 10.54 years (which is approximately the given time span of 10.5 years), two half-lives would have passed, confirming the half-life of cobalt-60 as 5.27 years.
This demonstrates a practical application of understanding radioactive decay and the significance of half-life in measuring how quickly unstable isotopes decline to half their original amount.
Unless it hits something, a bullet fired towards the sky experiences a constant rate deceleration as soon as it is fired from a gun.
True False
Got it right on the exam
This is easy, just read the last question. (Already Asked this question before)
How many grams of Sodium Hydroxide could be produced if 1.2L of 3.0 M Calcium Hydroxide are consumed?
Na2CO3 + Ca(OH)2 --> 2NaOH + CaCO3
Now I know how to do equations like this, just a bit confused on how to use my conversion factors.
Do I need to use the 3.0 Molarity in this equation or can I just use Molar Volume of a gas (22.4L/1 mole)?
You would have to use the molarity of calcium hydroxide to find the moles of calcium hydroxide. Once you have moles, just convert using mole:mole ratio and find the grams of sodium hydroxide.
Why do graphite and diamond appear to be different substances if they are composed of the same atom?
Answer:
Diamond and graphite are allotropes of carbon.
Explanation:
Diamond has a close packed crystal structure which is responsible for its extreme hardness. In it, each carbon atom is sp³ hybridised and bonded to four other carbon atoms in a tetrahedral arrangement. Diamond has a hardness of 10 on mohs scale with a cubic crystal form.
Note: allotropes of an element have different molecular structure.
Graphite on the other hand is made up of layers of hexagonal structure that are weakly bonded by van-der-waals forces. This layered arrangement explains its softness/slippery feeling and hence it is used as a lubricant. In each layer, each carbon atom is sp² hybridised and bonded to three other carbon atoms in a trigonal planar arrangement.
The presence of [tex]\pi[/tex] electrons in the layers accounts for its ability to conduct electricity.