Answer:
For the wavelenth of light spectrum, I believe the order would be red visible light, infrared, microwaves and radio waves.
What is the energy of a photon that emits a light of
frequency 6.42 x 1014 Hz?
A. 4.67 x 10-19 J
B. 4.25 x 10-19
C. 3.10 x 10-19 J
D. 9.69 x 10-19 J
Answer:
Option B is correct [4.25 x 10-19J]
Explanation:
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4.78×[tex]10^{-19}[/tex] J is the energy of a photon that emits light of
frequency 6.42 x[tex]10^{14}[/tex] Hz.
What is the frequency?Frequency is the rate at which current changes direction per second. The energy of a single photon is given by:
E =hν
where
E is the energy
h is the Planck constant
f is the frequency of the light
The chemical equation for the energy of a photon is given by:
E =hν , where h is the Planck constant and ν is the frequency.
E =hν = 6.626×[tex]10^{-34}[/tex] Js × 7.21×[tex]10^ {14}[/tex]
[tex]s^{-1}[/tex] = 4.78 ×[tex]10^{-19}[/tex] J
Hence, 4.78×[tex]10^{-19}[/tex] J is the energy of a photon that emits light of
frequency 6.42 x[tex]10^{14}[/tex] Hz.
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Silica (also known as silicon dioxide) reacts with hydrofluoric acid to produce silicon tetrafluoride and water vapor.
a) Write the balanced chemical equation for the reaction
b) 12.5 g of silicon dioxide is reacted with a 24.6 g of hydrofluoric acid. What is the theoretical yield of water vapor?
c) If the actual yield of water vapor is 2.50 g, what is the percentage yield of the reaction?
The problem is solved by balancing the reaction equation as shown below. The stoichiometry of the reaction is now applied in solving the question.
The balanced reaction equation is:
SiO2 + 6HF → H2[SiF6] + 2H2O
Using stoichiometry
The amount of silicon dioxide reacted = 12.5 g/60.08 g/mol = 0.21 mole
1 mole SiO2 yields 2 moles of H2O
0.21 mole of SiO2 yields 0.21 * 2/1 = 0.42 moles of H2O
The amount of HF reacted = 24.6 g/20.01 g/mol = 1.23 moles of HF
6 moles of HF yield 2 mole of H2O
1.23 moles of HF yields 2 * 1.23/6 = 0.41 moles of H2O
Hence HF is the limiting reactant.
Theoretical yield of H2O = 0.41 moles of H2O * 18 g/mol = 7.38 g
The percentage yield of the water is = actual yield/theoretical yield * 100
Hence;
% yield = 2.50 g/7.38 g * 100 = 33.9%
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Câu 1: Trong các dung dịch sau, dung dịch nào làm quỳ tím đổi màu xanh?
A. HCl B. H2SO4 C. NaOH D. NaCl
Câu 2: Bazơ nào dưới đây là bazơ không tan?
A. KOH B. NaOH C. Cu(OH)2 D. Ca(OH)2
Câu 3: Trong các chất sau đây, chất nào không phải là muối?
A. HCl B. KCl
C. NaOH
C. Cu (OH)
A. HCl
question 8 chemistry help
Answer:
Sorry,I can't do this because i don't know this questions answer.
Is backbonding is possible in BF4- ? If no then why?
Answer:
No, because Flourine can only form 1 bond, thus backbonding is not obtainable
Can you tell me name of Chemicals in food?
Answer:
Guar gum
sodium nitrite
artificial food colorings
monosodium glutamate
etc
A student in a lab holds an iron nail over an open flame, and no reaction occurs. The nail is then filed, creating small pieces of
iron shavings. These pieces burn brightly when placed over an open flame.
Which statement accurately identifies one of the changes that occurs as a physical or chemical change?
Formation of small pieces of iron shavings is a physical change whereas burning of pieces of iron shavings is chemical change.
Formation of small pieces of iron shavings is an example of physical change because it can be changed again into nail while on the other hand, burning of pieces of iron shavings on the flame is an example of chemical change because it can't change again into its original shape. Physical change is a change in matter which does not change the chemical properties of the matter whereas chemical change is a change in matter which change the chemical properties of the matter.
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9. a) Name salt that can be prepared by precipitation
I think its the substances that sublimes
A phase change from a solid to a gas is called:
Answer:
sublimation
Explanation:
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Resources found in lithosphere: gold and iron etc
Resources found in atmosphere: Water vapor, gases etc.
PLS HELP WILL GIVE BRAINLIEST
it is a simple chemistry question
i thought F has 9 electrons, so why does this structure show 8 electrons.
Answer:
The IUPAC structure only shows bond pairs and lone pairs. In the flouromethane structure above, there is only one bond pair and three lone pairs of electrons. Therefore there is one electron remaining, but since it doesn't not make up a pair, it is ignored in the structure but theoretically it is present.
[tex].[/tex]
Answer:
therefore there is one electron remaining , but since it doesn't make up a pair . It is ignored in the structure but theoretically it is present .
is (H) a positive or negative value
Answer:
A chemical reaction that has a positive ΔH is said to be endothermic , while a chemical reaction that has a negative ΔH is said to be exothermic . What does it mean if the ΔH of a process is positive? It means that the system in which the chemical reaction is occurring is gaining energy.
why can't sodium salt be prepared by double decomposition
Sodium salt might not be prepared by double decomposition because the method is used in preparing insoluble salts.
What is Double decomposition method?Double decomposition method serves as the method that is used in preparing compounds which entails reaction between two soluble compounds and after reaction soluble and insoluble products are produced.
Therefore, since most of the sodium salt are soluble salt , Double decomposition cannot be used to prepare them.
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If an atom has three shell and number of valence electrons are two. Is this element metal
or non-metal and why? Name the element and it’s valency.
Answer:
Metal
Element: Calcium
Valency: 2
Explanation:
To find the element, let's use the periodic table. (Look below)
We already went past 3 shells, just need the 2 electrons after it.
Just skip to the 4th row and count 2 to the right
We end up at Calcium.
Calcium is a metal and we're also on the alkaline earth metals column.
Calcium will need to lose 2 electrons to reach stability, so the valency is 2.
What is known about a reaction with a negative enthalpy?
A. The reaction is endothermic,
B. The reaction is spontaneous,
C. The reaction is exothermic,
D. The reverse reaction is favored,
Considering the definition of enthalpy of reaction, the correct answer is option C. a reaction with a negative enthalpy indicates that the reaction is exothermic.
Definition of enthalpy of reactionThe enthalpy of a chemical reaction as the heat absorbed or released when chemicals are transformed into a chemical reaction and it occurs at constant pressure.
The enthalpy is an extensive property, that is, it depends on the amount of matter present.
Finally, it must be taken into account that:
A reaction is called exothermic if its enthalpy of reaction is negative (that is, if the system gives up heat).A reaction is called endothermic if its enthalpy of reaction is positive (that is, if the system absorbs heat).SummaryIn summary, a reaction with a negative enthalpy indicates that the reaction is exothermic.
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precautive measures taken when using pooter
I guess ensuring that you don't suck the insects or specimen collected by ensuring there is a net in the pooter
Which statement best describes redox behavior in an electrochemical cell?
Electrons are produced at the copper rod.
Electrons flow from cathode to anode.
Reduction occurs at the zinc electrolyte.
Charges are balanced during redox.
Answer:
The last one
Explanation:
Charges are balanced in a redox reaction
The atomic number of silicon (Si) is 14. What's the electron configuration for silicon? Question 1 options:
A) [Ar] 3p5
B) [He] 1s2 2p6
C) [Ne] 3s2 3p2
D) [He] 2s2 3p2
Answer:
D.[Ne] 3S2 3P2
Explanation:
The electron configuration for silicon is [Ne] 3s² 3p². Hence Option (C) is correct.
What is elctronic configuration ?Electronic configuration, also called electronic structure or electron configuration, the arrangement of electrons in orbitals around an atomic nucleus.
The electron configuration of an element describes how electrons are distributed in its atomic orbitals.
Electron configurations of atoms follow a standard notation in which all electron-containing atomic subshells (with the number of electrons they hold written in superscript) are placed in a sequence.
Silicon belongs to group 14th and 3rd period.Therefore, The electron configuration for silicon is [Ne] 3s² 3p². Hence Option (C) is correct.
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The lattice energy for an ionic compound cannot be measured directly but can be calculated from the Born-_____ cycle, using a series of individual steps for which all enthalpies are known except for the lattice energy. This method is an application of Hess's law which, states that the overall energy change for a process is given by the _____ of the enthalpy changes for the individual steps.
Answer:
first is HABER
second is SUM
Explanation:
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5. What change would increase the amount of gas able to be dissolved in a given amount of liquid water? (2 points)
Increasing temperature
a
Increasing pressure
Increasing surface area
O
Increasing rate of stirring
answer : increasing pressure
the amount of gas that can be dissolved in liquid water increase with the increase in pressure
Answer:
increasing pressure
Explanation:
Patience, a popular card game in Mendeleev's time, is also known as Go Fish.
A. True
B. False
Answer:
B. False
Explanation:
step by step explanation
Answer:
False
Explanation:
breaking larger molecules into smaller molecules and carbon
Answer: catabolism
Explanation:
Catabolism refers to the set of metabolic pathways which is necessary for the breaking down of molecules into smaller units. This is then oxidized for the release of energy or can be used to perform other anabolic reactions.
Catabolism is regarded as the opposite direction of anabolism which is simply the building-up of molecules. It should be noted that anabolism and catabolism work together in every living organisms and perform functions such as the production of energy and the repair of cells.
the smell spreads immediately after you burn agarbatti in this example what is your condition about intermolecular force
Answer:
The aroma of agarbatti spreads quickly once you burn it because the particles in the agarbatti move endlessly in all directions. Both, the air and aroma, have large intermolecular forces which is why the molecules of air scatter immediately once agarbatti is burned.
Energy in the amount of 420 J is added to a 35 g sample of water at a temperature of 10°C. What is the final temperature of the water?
The final temperature of the water, T2 = 38.57°C
Temperature can be defined as a measure of the degree of hotness or coldness of a physical object (body). Thus, it is measured with a thermometer and its units are degree Celsius (°C), Fahrenheit (°F) and Kelvin (°K).
A calorie refers to the amount of heat required to raise the temperature of a gram of water by one (1) degree Celsius (1°C).
Given the following data:
Quantity of energy = 420JMass = 35 gramsInitial temperature, T1 = 10°CThe specific heat capacity of water is 4.2 J/g°C.
To find the final temperature of the water (T2):
Mathematically, the quantity of energy (heat capacity) is given by the formula;
[tex]Q = mcdt[/tex]
Where;
Q represents the heat capacity or quantity of heat.M represents the mass of an object.C represents the specific heat capacity of water.dt represents the change in temperature.Substituting the values into the formula, we have;
[tex]420 = 3.5 \; * \; 4.2 \; * \; dt[/tex]
[tex]420 = 14.7 \; * \; dt\\\\dt = \frac{420}{14.7}[/tex]
Change in temperature, dt = 28.57°C
Next, we would solve for the final temperature by using this formula;
[tex]dt = T2 - T1[/tex]
[tex]28.57 = T_{2} - 10\\\\T_{2} = 28.57 \; + \; 10\\\\T_{2} = 38.57[/tex]
Final temperature, T2 = 38.57°C
Therefore, the final temperature of the water, T2 is equal to 38.57°C
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what do you mean by acceleration due to gravity of a body is 10 metre per second square
Answer:
If a body is accelerated by 10m/s^2, it means that the body's speed (or velocity to be precise) is increasing by 10m/s every second. That is, if the initial ...
Which phrase correctly describes the molecular structure within a molecule?(1 point)
A the location of atoms, groups, or ions relative to one another and the number, type, and location of covalent bonds
B long, repeating chains of molecules
C the smallest fundamental unit of a compound that participates in reactions, represented by a bonded group of atoms
D the basic unit of a chemical element
Answer: A the location of atoms, groups, or ions relative to one another and the number, type, and location of covalent bonds
Explanation: I just took the assessment and in my notebook molecular structure has a definition that is literally answer A. Also I got it right lol.
what is the requirements to obtain citizenship?
please answer it correctly
Answer:
Age. ...
Residency. ...
Residence and Physical Presence.
Good Moral Character.
Attachment to the Constitution.
Language.
U.S. Government and History Knowledge.
Oath of Allegiance.
These are some requirements for obtaining citizenship .
Plz help me with this question
Drawing of water molecular formulas
1.Draw molecular structure of water
Answer:
Here is your answer. I hope it will help you .what is the purest form of iron
I need help please!!!!!
Answer:
sorry..,...........
.....
