Answer:
1. Neutron number = 43
2. Proton number = 34
3. Electron number = 36
Explanation:
From the question given above, the following data were obtained:
Mass number = 77
Charge of ion = –2
1. Determination of the number of neutron.
Mass number of Se = 77
Atomic number = 34
Neutron number =?
NOTE: Atomic number = proton number
Mass number = Proton + Neutron
77 = 34 + Neutron
Collect like terms
77 – 34 = Neutron
Neutron number = 43
2. Determination of the proton number.
The atomic number of an element is simply defined as the number of protons in the atom of the element. Mathematically,
Atomic number = Proton number
Atomic number of Se = 34
Therefore, the proton number of Se²¯ is 34.
NOTE: The atomic number does not change be it atom, ion or molecule. It remains the same.
3. Determination of electron number.
Charge of ion = –2
Proton number = 34
Electron number =?
Proton – Electron = Charge
34 – Electron = –2
Rearrange
34 + 2 = Electron
36 = Electron
Electron number = 36
There are 43 neutrons, 34 protons, and 36 electrons in the given selenium ion with a (-2) charge.
Explanation:
Given:
A selenium ion with a mass number of 77 and a charge of (-2).
To find:
The number of neutrons, protons, and electrons in selenium ion
Solution:
Charge on the selenium ion = -2
The atomic number of selenium = 34
Number of protons = Atomic number
Number of protons in selenium atom = 34
Number of protons in selenium ion = 34
Number of electrons in selenium atom = 34
Number of electrons in selenium ion= 34+2 = 36
(anion is formed by gaining of electrons that is why adding two electrons )
The mass number of selenium = 77
Mass number = Number of protons + Number of neutrons
77 = 34 + Number of neutrons in selenium
Number of neutrons in selenium ion = 77 - 34 = 43
There are 43 neutrons, 34 protons, and 36 electrons in the given selenium ion with a (-2) charge.
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HCl + Fe?ra gì hihihihi
Answer:
fecl2+ h2
Explanation:
How much heat must be transferred to 1600 g of iron to change the iron's
temperature from 202°C to 214°C? (The specific heat capacity of iron is
0.450 J/g.°c.)
O A. 8600 J
O B. 3.4 J
O C. 300
O D. 60 J
Answer:
A. 8600 J
General Formulas and Concepts:
Thermochemistry
Specific Heat Formula: q = mcΔT
q is heat (in J)m is mass (in g)c is specific heat (in J/g °C)ΔT is change in temperature (in °C)Explanation:
Step 1: Define
[Given] m = 1600 g
[Given] ΔT = 214 °C - 202 °C = 12 °C
[Given] c = 0.450 J/g °C
[Solve] q
Step 2: Find Heat
Substitute in variables [Specific Heat Formula]: q = (1600 g)(0.450 J/g °C)(12 °C)Multiply [Cancel out units]: q = (720 J/°C)(12 °C)Multiply [Cancel out units]: q = 8640 JStep 3: Check
Follow sig fig rules and round. We are given 2 sig figs as our lowest.
8640 J ≈ 8600 J
Topic: AP Chemistry
Unit: Thermodynamics
When a catalyst is added to a chemical reaction it provides a new reaction pathway that results in a different
Answer: That results in a different ALTERNATE pathway which has a LOWER ACTIVATION ENERGY.
Explanation:
There are many factors that affects a chemical reaction, these include'
--> surface area
--> concentration,
--> temperature,
--> pressure and
--> presence of CATALYST.
A CATALYST is defined as the substance that has the ability to alter the rate of a chemical reaction. Many reaction very slowly when left alone, but become faster when other substances are added. Such substances that merely alter the rate of reactions but do not take part in the reactions are called CATALYSTS.
Activation energy is defined as the energy barrier that must be overcome before a reaction takes place. A catalyst is able to increase the rate of a chemical reaction by decreasing the activation energy of the chemical system.
A catalyst provides an ALTERNATE PATHWAY for the reaction that has a LOWER ACTIVATION ENERGY. When activation energy is lower, more reactant particles have enough energy to react, so the reaction occurs faster.
Heavy rains fill a reservoir, causing the dam that holds the water to break. As a result, the areas downstream are suddenly flooded. Which question would a scientist seek to answer?
Answer:
"How to prevent the collapse of the dam that contains water from heavy rains?"
Explanation:
Scientists must work to create innovations capable of bringing benefits to human life and combating disadvantageous and harmful situations. The overflow of dams is something very harmful, as the resulting flooding can cause structural, economic and even public health problems. When this overflow is caused by natural elements, such as heavy rains, the work of scientists in solving these issues is even more important and necessary. In order to resolve the dam failure caused by excess rainwater, scientists must work to answer the following question:
"How to prevent the collapse of the dam that contains water from heavy rains?"
how many different sublevels are in the second energy level?
2
1
4
3
Answer:
The answer is 2
Explanation:
There are two energy sublevels in the second principal energy level. These two energy sublevels are 2s and 2p. The energy distribution in an atom is divided into a number of principal energy levels, and the principal energy levels are again divided into four basic energy sublevels.
Define the boiling and evaporation using kinetic theory
Answer:
Explanation:
By the kinetic molecular theory (particle model), all matter consists of particles, there are spaces between the particles, the particles are in constant random motion, and there are forces of attraction and repulsion between the particles.
Furthermore, temperature is defined to be a measure of the average kinetic energy of the particles.
Evaporation is a change of phase from liquid to gas explained as follows :
When particles in the liquid phase are heated, they gain kinetic energy and move faster and further apart. Eventually they have enough energy to escape the forces of attraction holding them together in the liquid phase and they move very fast and far from each other and exist in the gaseous phase.
7. You have 1.5x1024 atoms of iron. How many moles do you have?
Answer:
2.49moles
Explanation:
To calculate the number of moles (n), of iron (Fe) in 1.5 × 10²⁴ atoms, we divide the number of atoms by Avogadro's number (6.02 × 10²³).
That is, n = N ÷ nA
Where;
n = number of moles (mol)
N = number of atoms
nA = Avogadro's constant
n = 1.5 × 10²⁴ ÷ 6.02 × 10²³
n = 1.5/6.02 × 10(²⁴ - ²³)
n = 0.249 × 10¹
n = 2.49moles
rank the intermolecular forces from weakest to strongest. Dipole-induced dipole, London dispersion, hydrogen bond, dipole-dipole
Answer:
London dispersion,hydrogen bond, dipole-dipole,dipole-induced dipole.
Explanation:
London dispersion < hydrogen bond < dipole-dipole < dipole-induced dipole.
What are intermolecular forces?Intermolecular forces are the forces which mediate an interaction between molecules, including forces of attraction or repulsion which act between molecules and other types of neighbouring particles.
The London dispersion force is a temporary attractive force that occurs when the electrons in two adjacent atoms make atoms form temporary dipoles.
A hydrogen bond is an intermolecular force that occurs with a special type of dipole-dipole attraction.
Dipole-dipole forces are the forces between the positive side of one polar molecule and the negative side of another polar molecule.
A dipole-induced dipole attraction is a weak attraction that occurs when a polar molecule produces a dipole in an atom or in a nonpolar molecule by arranging of electrons in the nonpolar species.
Hence intermolecular forces from weakest to strongest are:
London dispersion < hydrogen bond < dipole-dipole < dipole-induced dipole.
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A se ion has a mass number of 77
and a charge of −2
. Determine the number of neutrons, protons, and electrons in this ion.
Answer: The number of protons are 34, number of neutrons are 43 and number of electrons are 36 in the given Se ion
Explanation:
The atom consists of 3 subatomic particles:
Protons: They are positively charged particles present in the nucleus of an atom.Electrons: They are negatively charged particles present in the orbits around the nucleus of an atom.Neutrons: They are neutral particles present in the nucleus of an atom.The mass number is the sum of the number of protons and number of neutrons in the nucleus of an atom. These are known as nucleons
The atomic number is defined as the number of electrons or number of protons present in an atom.
We are given:
A Se ion having mass number 77
Atomic number of Se = 34
Number of protons = 34
Number of neutrons = 77 - 34 = 43
Number of electrons = Atomic number - Charge
Charge = -2
Number of electrons = [34 - (-2)] = [34 + 2] = 36
Hence, the number of protons are 34, number of neutrons are 43 and number of electrons are 36 in the given Se ion
what type of chemical is manganese(IV) oxide
Answer:
catalyst
Explanation:
it alters the speed of reaction
Which of the following is true of science?
O It can be disproven by philosophy and religion.
O It does not change after new evidence is discovered.
O It is based on the personal opinions of scientists.
O It is based on testable and replicable evidence.
Answer:
I know the other person already said this but it would be the last option : )
0.18 g of a divalent metal was completely dissolved in 250 cc of acidsolution containing 4.9 g H2SO4 per liter. 50 cc of theresidual acid solution required 20 cc of N/10 alkali forcomplete neutralization. Calculate the atomic weight of metal.
goodnight Gucci chunk cubic DDF if f Ch BK
What is pH?
O A. A measurement indicating how acidic a solution is
B. A concentration of total ions dissolved in solution
C. A level of dissolved gases that are in solution
O D. A component of solutions that makes them acidic
Answer:
Awnser is A
Explanation:
Answer:
Hello There!!
Explanation:
The answer is↬O A. A measurement indicating how acidic a solution is.
hope this helps,have a great day!!
~Pinky~
Es para hoy, ayuda por favor
Answer: it)s not letting me download it edit it a d re send it
Explanation:
this is already solved but i would appreciate if someone check for me. thank you !
Question 24 Multiple Choice Worth 2 points)
[BWS.02] Why is science important for society?
Answer:
Because the scientific knowledge itself helps solve many basic human needs and it also improves how humans live and their standards. For example, without science medications wouldn´t exist and many technological devices we use now-a-days. We´re surrounded by science, we just don´t really notice it.
Physical properties can be divided into two categories. _______ depend on the amount of matter present, while _______ don't.
Name the following aromatic hydrocarbon:
Explanation:
I think option 3..............
CH3COOH
a. What is hydrated water?
1
b. How sodium hydrogen carbonate blow up
cake?
2
c. Explain the cause of saying that the reaction no. (ii) is a
hydrolysis reaction.
3
d.) Is the reaction no. (i) said a redox reaction and a
substitution reaction simultaneously? Analyze with
equations.
4
Answer:
the water which are very healthy is known as hydrated water
Help me with this question
Define a unit? write it's type
Answer:
Unit is the standard assigned to measure physical quantity. ... Length, mass, time, temperature, luminous intensity, and the electric current are known as the fundamental quantities. These are represented by L, M, T, 0, Cd, and A respectively
OAmalOHopeO
3 Cu + 8HNO3 → 3 Cu(NO3)2 + 2 NO + 4 H2O
In the above equation, how many grams of water can be made when 15.9 moles of HNO3 are consumed?
Answer:
45673
Explanation:
Which of the following compounds is usually
added to a swimming pool to prevent the growth
of algae ?
A. Caso
B. Cuso
C. PbSO
D. MgSO
4
4
4
4
what mass of water will be formed when 3g of hydrogen react with 30g of oxygen?
Answer: Write down the chemical equation first;
2H2 + O2 —-> 2H2O
2. Since the mass is given, use it to calculate the mole for each reactant;
mole = mass / molar mass
mole of H2 : 8/2 = 4 mole
mole of O2 : 30/16(2) = 0.9375 mole
Now, if you're not sure which reactant to use to calculate the mass of H2O using ratio since both answer are different, find the limiting reactant.
From the equation;
2 mol of H2 -> 2 mol of H2O
4 mol of H2 -> (4*2)/2 = 4 mol of H20
______________________________________
1 mol of O2 -> 2 mol of H2O
0.9375 mol of O2 -> (0.9375*2)/1 = 1.875 mol of H2O
Let's take a look at both numbers. Since H2 produces more water than O2, O2 will be the limiting reactant as it has the least mole of H2O. So now we are going to use O2 as our limiting reactant. Use the formula to calculate mass of water using mole.
mass of H2O : 1.875*(16+2) = 33.75 g
Thats it. Correct me if im wrong
Explanation:
List the two pairs of atoms referred to in the
previous question in order of increasing ionic
character of the bonding between them.
Which coefficients correctly balance the formula equation below?
AgNO3 + CuCl2 → AgCl + Cu(NO3)2
2, 1, 2,1
1, 1, 3,1
2, 2, 3,1
2, 1, 1,2
Answer:
2, 1, 2,1
Explanation:
The chemical equation of the reaction given in this question is as follows:
AgNO3 + CuCl2 → AgCl + Cu(NO3)2
The reaction is between silver nitrate (AgNO3) and copper (I) chloride (CuCl2) to form silver chloride (AgCl) and copper nitrate (Cu(NO3)2.
However, this above equation is not BALANCED because the number of atoms of each element on both sides of the equation does not equate i.e. are not the same. To balance the equation, we have to make use of COEFFICIENTS, which are numbers used in front of each element in order to balance the equation.
The balanced equation is as follows:
2AgNO3 + CuCl2 → 2AgCl + Cu(NO3)2
From the above balanced equation, we can observe that coefficients used to balance the equation is in the order: 2, 1, 2,1
A student is investigating the effect of concentration on the colour of a solution of copper sulfate.She wished to make up 250cm^3 of a solution if copper sulfate with a concentration of 0.5 mol/dm^3 that she can dilute. a solution with the concentration of 0.50 mol/dm^3 contains 0.50 mol of copper sulfate per decimetre cubed calculate the concentration of this solutionin g/dm^3
Answer:
79.8g/dm³
Explanation:
As you can see, the solution in the problem contains 0.5 moles of copper sulfate per dm³. To solve this question we must convert these moles to grams using its molar mass (Molar mass CuSO4 = 159.609g/mol) as follows:
0.5mol CuSO4/dm³ * (159.609g/mol) =
79.8g/dm³The Sulphate of x is XSO4 valency of x is
Answer: m mm
/lk ac
Explanation:
Gatorade has the conductivity of 3296 µS, Powerade has 4502 µS, and Vitamin Water is 657 µS. What does this data tell you about the dissolved ions in these solutions?
Answer:
Powerade has the most dissolved ions, followed by Gatorade and lastly vitamin water
Explanation:
How conductive a certain solution is, is based on the kind of ions that are present or dissolved in the solution. Hence, we have it that, the higher the concentration of the ions that are present in a solution, the better it will conduct.
There is thus, a direct relationship between what is dissolved or the kind of present ions and how conductive the solution is.
A solution with more dissolved ions is a better conductor of electricity and thus has a conductivity value that is higher
Thus, we can conclude that Powerade has more dissolved ions, Gatorade has less and Vitamin water has the least
set goals and objectives for a company
Explanation:
Objectives and goals serve as a foundation for successful organizations since they establish the business's objective and aid in the identification of required measures. Goals are broad assertions of what you want to achieve, whereas goals are the precise stages or steps you need to take to get there.
What is the pOH of a 1 x 10^-8 M solution of HNO3?
Explanation:
to find POH u need PH first
so ph=-log(h3o)
so
[tex]ph = - log(1 \times {10}^{ - 8} ) \\ \\ ph = 8 \\ ph + poh =14 \\ poh = 14 - 8 \\ poh = 6[/tex]