1 endothermic 2 yes and exothermic 3 endothermic
Why do you think elements have these repeating patterns and groups of similar elements ? Explain your reasoning as much as you can.
Answer:
The elements in the periodic table are arranged in order of increasing atomic number. All of these elements display several other trends and we can use the periodic law and table formation to predict their chemical, physical, and atomic properties. Understanding these trends is done by analyzing the elements electron configuration; all elements prefer an octet formation and will gain or lose electrons to form that stable configuration.
Please give me brilliant answer
Two objects are described below.
Object 1: A skateboard with unbalanced forces
Object 2: A bicycle with balanced forces
Which statement is true about the objects?(2 points)
Both objects are moving.
Both objects are not moving.
Object 1 is moving, and Object 2 is not moving.
Object 1 is not moving, and Object
Answer:
Both objects are moving.
Explanation:
Object 1 is moving because the unbalanced force acting on the skateboard is causing it to either move slower or move faster. An example of this is when the skateboard is going down the hill. The unbalanced force is caused by the gravity which speeds up the skateboard.
Object 2 is also moving although it has a balance force; however, it is moving at a "constant speed." This is because the force of thrusting forward is being counteracted by a friction force of the same magnitude. Forces that are equal in magnitude and of opposing directions causing the speed to be constant. So, the bicycle is still moving.
Blood samples for research or medical tests sometimes have heparin added. Why is this done?
Indium-116 is radioactive and has a half life of 14.10 seconds. How long would it take a sample to decay from 7.70 mg to 900 µg.
Answer: 43.73 seconds
Explanation:
Half-life of indium = 14.10 sec
First we have to calculate the rate constant, we use the formula :
[tex]k=\frac{0.693}{t_\frac{1}{2}}[/tex]
[tex]k=\frac{0.693}{14.10}=0.0491sec^{-1}[/tex]
Now we have to calculate the age of the sample:
Expression for rate law for first order kinetics is given by:
[tex]t=\frac{2.303}{k}\log\frac{a}{a-x}[/tex]
where,
k = rate constant
t = age of sample = ?
a = initial amount of the reactant = 7.70 mg= [tex]7700\mug[/tex]
[tex](1mg=1000\mug[/tex]
a - x = amount left after decay process = [tex]900\mug[/tex]
Now put all the given values in above equation, we get
[tex]t=\frac{2.303}{0.0491}\log\frac{7700}{900}[/tex]
[tex]t=43.73sec[/tex]
Thus it would take 43.73 seconds sample to decay from 7.70 mg to 900 µg.
The analysis of a compound containing K, P and O showed 55 % K, 15 % P and 30 % O, set up the simplest empirical formula of this compound.
Answer:
Empirical formula is K₃PO₄.
Explanation:
Given data:
Percentage of K = 55%
Percentage of P = 15%
Percentage of O = 30%
Empirical formula = ?
Solution:
Number of gram atoms of K = 55 / 39.098 = 1.41
Number of gram atoms of P = 15 /30.974= 0.48
Number of gram atoms of O = 30 / 15.999 = 1.88
Atomic ratio:
K : P : O
1.41/0.48 : 0.48/0.48 : 1.88/0.48
3 : 1 : 4
K : P : O = 3 : 1 : 4
Empirical formula is K₃PO₄.
What's the molality of a solution with 120 g of NaCl and 30 kg of water?
Answer:
0.07mol/kg
Explanation:
Given parameters:
Mass of NaCl solution = 120g
Mass of water = 30kg
Unknown:
Molality of the solution =?
Solution:
The molality of a solution is the number of moles of the solute per mass of the solution.
Molality = [tex]\frac{number of moles of solute}{mass of solution}[/tex]
Number of moles of NaCl = [tex]\frac{mass}{molar mass}[/tex]
Molar mass of NaCl = 23 + 35.5 = 58.5g/mol
Number of moles of NaCl = [tex]\frac{120}{58.5}[/tex] = 2.05mole
So;
molality = [tex]\frac{2.05}{30}[/tex] = 0.07mol/kg
Answer:
0.068
Explanation:
If 11.2 g of naphthalene, C10H8, is dissolved in 107.8 g of chloroform, CHCl3, what is the molality of the solution?
a. 0.811m
b. 0.0941 m
c.12.4 m
d. 0.0875 m
e. 0.0969m
Answer: 0.811m
Explanation: Molarity is the moles of solute present per kg of solvent.
Molar mass of C10H8 = . 128.17 g/mol
No. of moles = given mass/molar mass
11.2g C10H8 = 11.2/128.17 g/mol C10H8
= 0.0874 mol C10H8
NOW 107.8g solvent (chloroform) contains 0.0879 molecules (naphthalene)
1000g '' will contain (0.0879/107.8 x 1000) mole solute
= 0.811 mole
Molarity of the solution is 0.811 m (option A)
Where do genetic traits originate and how are they passed from one generation to the next?
How many pi bonds are in the oxalate ion (C2O42-)?
Answer:there are 13
Explanation:
There are two types of chemical compound one is covalent compound and another is ionic compound in chemistry. In ionic bonds, electrons are completely transferred. Therefore, there are 2 pi bonds in oxalate ion C[tex]_2[/tex]O[tex]_4[/tex]²⁻.
What is chemical Compound?Chemical Compound is a combination of molecule, Molecule forms by combination of element and element forms by combination of atoms in fixed proportion.
Covalent compounds are formed by covalent bond and ionic compounds are formed by ionic bond. Covalent bond is formed by sharing of electron and ionic bond are formed by complete transfer of electron. Ionic bonds are stronger than covalent bonds. The melting and boiling points are higher in ionic compounds. There are total 2 pi bonds in oxalate ion C[tex]_2[/tex]O[tex]_4[/tex]²⁻.
Therefore, there are 2 pi bonds in oxalate ion C[tex]_2[/tex]O[tex]_4[/tex]²⁻.
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For the following reaction (production of ethanol) C2H4 +H2O——>C2H5OH
A. How many moles of water will be used to produce 10 mol of C2H5OH
B. If you need to produce 27 mol C2H5OH how many moles of C2H4 will be used?
Answer:
A: 10 moles of water are required.
B: 27 moles of C₂H₄ are used.
Explanation:
A:
Given data:
Moles of water used = ?
Moles of C₂H₅OH formed = 10 mol
Solution:
Chemical equation:
C₂H₄ + H₂O → C₂H₅OH
Now we will compare the moles of water with C₂H₅OH from balance chemical equation:
C₂H₅OH : H₂O
1 : 1
10 : 10
10 moles of water are required.
B)
Given data:
Moles of C₂H₄ used = ?
Moles of C₂H₅OH formed = 27 mol
Solution:
Chemical equation:
C₂H₄ + H₂O → C₂H₅OH
Now we will compare the moles of C₂H₄ with C₂H₅OH from balance chemical equation:
C₂H₅OH : C₂H₄
1 : 1
27 : 27
27 moles of C₂H₄ are used.
You are asked to determine the identity of an unknown liquid and can measure only one physical property. You heat the liquid and record that the liquid turns to vapor at 100°C.
Which physical property does this demonstrate?
A. boiling point
B. malleability
C. ability to conduct electricity
D. melting point
Answer:
A. boiling point
Explanation:
I'm not good at explaining science but...
Heating- keyword
I would take out b and c because you don't need heat for those.
When it's liquid, it would boil, not melt.
Vapor is also a sign of boiling.
how many neutrons does an atom of Vanadium contain
Answer: 28
Explanation:
Classify the following bonds as ionic, polar cova-
lent, or covalent, and give your reasons: (a) the
SiSi bond in Cl3SiSiCl3, (b) the SiCl bond in
Cl3SiSiCl3, (c) the CaF bond in CaF2, (d) the NH
bond in NH3.
Answer:
a) Covalent
b)Polar Covalent
c)Ionic
d)Coordinate Covalent
Explanation:
The SiSi bond in Cl3SiSiCl3 is covalent, the SiCl bond in Cl3SiSiCl3 is polar covalent, the CaF bond in CaF2 is ionic and the NH bond in NH3 is covalent.
What is covalent bond?The covalent bond is defined as a chemical bond that involves sharing of an electron pair between the atoms.
A covalent bond formed when there difference is the electronegativities of two atoms is too small for an electron transfer to occur to form ions.
The ionic bond is defined as a form of a chemical connection in which one atoms loses valance electrons and gain them from another.
A ionic bond is formed by interaction of oppositely charge ions .
Thus, SiSi bond in Cl3SiSiCl3 is covalent, the SiCl bond in Cl3SiSiCl3 is polar covalent, the CaF bond in CaF2 is ionic and the NH bond in NH3 is covalent.
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The orbital diagram above is from the element ?
Answer:
Phosphorus
Explanation:
In given diagram there are 15 electrons are present. Which means it is orbital diagram of phosphorus.
The atomic number of phosphorus = 15
Number of electrons = 15
Electronic configuration of phosphorus:
P₁₅ = 1s² 2s² 2p⁶ 3s² 3p³
All other options are incorrect because:
Calcium have 20 electrons.
Electronic configuration of Ca:
Ca₂₀ = 1s² 2s² 2p⁶ 3s² 3p⁶ 4s²
Hydrogen have one electron.
Electronic configuration of H.
H₁ = 1s¹
Magnesium have 12 electrons:
Electronic configuration of Mg:
Mg₁₂ = 1s² 2s² 2p⁶ 3s²
When a solid reaches its melting point, what happens? 1. melting 2. freezing. 3. vaporization 4. boiling
There is a concentrated (12.0 M) solution of HCl in the lab storage area. You need to prepare 1600. mL of HCl solution that has a pH equal to 1.50.
a) What volume of the 12.0 M HCl solution do you need?
b) What volume of water do you need?
a. 0.00426 L
b. 1.596 L
Further explanationThe number of moles in dilution will remain constant
Can be formulated
[tex]\tt M_1.V_1=M_2.V_2[/tex]
a.
M₁=12
M₂=[tex]\tt 10^{-1.5}(pH=-log[H^+])[/tex]=0.032
V₂=1.6 L
[tex]\tt 12\times V_1=0.032\times 1.6\\\\V_1=0.00426~L[/tex]
b.
[tex]\tt 1.6-0.00426=1.596~L[/tex]
What is the frequency of a photon that has 3.82 x 10^-20 J of energy?
Answer:
5.73498*10^13
Explanation:
............
which compound has covalent bonds? H2O, Li2O, Na2O, K2O
Answer:
H2O
Explanation:
H2O is just given as a covalent compound... Usually covalent bonds occur between 2 or more nonmetals.
Water or H₂O is a compound which has covalent bonds as there is slight difference in electronegativity of hydrogen and oxygen atoms.
What is a covalent bond?
Covalent bond is defined as a type of bond which is formed by the mutual sharing of electrons to form electron pairs between the two atoms.These electron pairs are called as bonding pairs or shared pair of electrons.
Due to the sharing of valence electrons , the atoms are able to achieve a stable electronic configuration . Covalent bonding involves many types of interactions like σ bonding,π bonding ,metal-to-metal bonding ,etc.
Sigma bonds are the strongest covalent bonds while the pi bonds are weaker covalent bonds .Covalent bonds are affected by electronegativities of the atoms present in the molecules.Compounds having covalent bonds have lower melting points as compared to those with ionic bonds.
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Why did the hot water rise? Use faster, molecules, energy, density in your answer.
Answer:
Convection
Explanation:
Hot water will rise due to heat transfer by convection occurring in the heating system.
When a fluid is heated, the molecules will gain thermal energy. As the thermal energy of the liquid increases, the molecules will have heat which is average kinetic energy in the system. This causes them to be less denser and they rise in the cooking medium. As they rise, the colder part of the water sinks down to replace them in the pot. This exchange sets up convection cells in the heating medium.Calculate the heat of reaction AH for the following reaction:
2 HCl(g) + F2(g) → 2 HF(g) + Cl2(9)
Answer:
can u give the bond energies
3. Which has the largest atomic radius? *
O Calcium
0 Iron
Gallium
O Bromine
Answer:
the correct answer is calcium becuase it is over 200.
Explanation:
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Assuming complete dissociation of the solute, how many grams of KNO3 must be added to 275 mL of water to produce a solution that freezes at −14.5 ∘C
Answer:
108.43 grams KNO₃
Explanation:
To solve this problem we use the formula:
ΔT = Kf * b * iWhere
ΔT is the temperature difference (14.5 K)Kf is the cryoscopic constant (1.86 K·m⁻¹)b is the molality of the solution (moles KNO₃ per kg of water)and i is the van't Hoff factor (2 for KNO₃)We solve for b:
14.5 K = 1.86 K·m⁻¹ * b * 2b = 3.90 mUsing the given volume of water and its density (aprx. 1 g/mL) we calculate the necessary moles of KNO₃:
275 mL water ≅ 275 g water275 g /1000 = 0.275 kgmoles KNO₃ = molality * kg water = 3.90 * 0.275moles KNO₃ = 1.0725 moles KNO₃Finally we convert KNO₃ moles to grams, using its molecular weight:
1.0725 moles KNO₃ * 101.103 g/mol = 108.43 grams KNO₃What happens in the redox reaction below? Select all that apply.
Na + F + NaF
A- Fluorine loses an electron.
B- Sodium loses an electron.
C- Sodium gains an electron.
D- Fluorine gains an electron.
E- Sodium is oxidized.
Answer:
B- Sodium loses an electron.
D- Fluorine gains an electron.
Sodium is oxidized.
Explanation:
The reaction equation is given as:
Na + F → NaF
In this reaction, Na is the reducing agent. It loses an electron and then becomes oxidized. By so doing, Na becomes isoelectronic with Neon.
Fluorine gains the electron and then becomes reduced. This makes fluorine also isoelectronic with Neon.
This separation of charges on the two species leads to an electrostatic attraction which forms the ionic bonds.
Consider the temperature versus time graph below. A graph of temperature versus time has time on the horizontal axis and temperature in degrees Celsius from negative 20 to 140 on the vertical axis. A line extends through the following points: 0, negative 10; 4, 0; 7, 140; 18, 120; 19, 125. At what temperature is the substance a heated gas? at 100°C below 0°C above 100°C between 0°C and 100°C
Above 100°Celsius is the temperature at which the substance is converted into a gas.
Different liquids have different boiling points at which they change from liquid to gaseous state. The boiling point of water is 100°Celsius means at 100°Celsius or above temperature, the water changes from liquid form into gas form or vapour form so we can conclude that at high temperature i.e. above 100°Celsius the substance is converted from liquid state to gaseous state.
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The mercury-201 nuclide radioactively decays by electron capture. Write a balanced nuclear chemical equation that describes this process.
Answer:
Explanation:
Electron capture is a form of beta decay in which the nucleus of a radionuclide captures an electron. In the case of mercury-201, the equation below illustrates that
²⁰¹₈₀Hg + ⁰₋₁e ⇒ ²⁰¹₇₉Au
As can be seen above, the electron capture reduces the atomic number by one unit leading to the production of a new radioisotope (because of the change in atomic number).
Relation between glancing and angle of deviation
Answer:
the Glancing angle is the angle between the incident ray and plane mirror which is 90o in the given case. The angle between the direction of the incident ray and the reflected ray is the angle of deviation. Since the angle of deviation for a plane mirror is twice the glancing angle, the angle of deviation is 1800.
20 POINTS + BRAINLIEST, HELP
Answer:
B
Explanation:
You add them all together if I'm correct. (I'm in middle school so don't get mad if its wrong lol)
Answer: 4) 2.5
Step-by-step explanation:
The ratio of line segments as per picture
5/x = 4.6/2.3
x = 2.5
Correct option is
4) 2.5
Explanation:JK ITS B.
Suppose a metal will eject electrons from its surface when struck by yellow light. What will happen if the surface is struck with ultraviolet light?
a. No electrons would be ejected.
b. Electrons would be ejected and they would have lower kinetic energy than those ejected by yellow light.
c. Electrons would be ejected and they would have the same kinetic energy by yellow light.
d. Electrons would be ejected and they would have greater kinetic energy than those ejected by yellow light.
Answer:
d. Electrons would be ejected and they would have greater kinetic energy than those ejected by yellow light.
Explanation:
A formula that describes the kinetic energy of an electron ejected when a surface is truck by light is:
Ephoton = KineticEnergyElectron + ΦAs you see, the higher the energy of the photon striking the surface, the higher the kinetic energy of the ejected electron.
Ultraviolet light has more energy than yellow light, so it would cause the ejected electron to have greater kinetic energy as well.
More points for the world
Answer:
thaaaaaaaaaaaannnnkssss
Explanation:
sssssssssssssss
Answer:
jgiuufiydifiydifiyfkhditdihfkcgdraoyfufhkdoyfhvljcohchochcofohfoydoyfiyfohc
Explanation:
kxydutdoufuodyiflfjslufkysluftwykdhmdtwkggjaurq arrival arrival
sodium chloride is made from sodium and chloride. would you expect the properties of sodium chloride to be simliar to sodium or cloride
Answer:
No
Its a chemical change so the characteristics or chemical properties always differs thereby the properties of sodium chloride isn't similar to sodium or chloride