The enthalpy of formation of liquid mercury and gaseous chlorine are zero because the substance are in their standard state.
The standard state of a substance is the form in which it is found under standard conditions. This include a pressure of 1 atm, a temperature of 298 K and a a concentration of 1 M.
The enthalpy of formation of a substance in its standard state is 0 KJ/mol. The following substances has ΔHf of 0 kJ/mol.
ΔHf of Hg(I) is 0 kJ/mol. ΔHf of Cl2(g) is 0 kJ/molLearn more: https://brainly.com/question/13164491
why do the noble gases have relatively low electron affinities?
Answer:
Because noble gases have a full octet, their ionization energies are actually quite high. Electron affinity is the amount of energy released when an electron is added to a neutral atom. Because noble gases have stable electron configurations, they have very low electron affinities.
Explanation:
Answer:
Noble gases have a stable outer shell
Explanation:
Which models of the atom in task 1 are not supported by the results of the hydrogen gas experiment? For each of these models, explain the experimental results that the model would predict.
Answer:
Thomson placed two magnets on either side of the tube, and observed that this magnetic field also deflected the cathode ray. The results of these experiments helped Thomson determine the mass-to-charge ratio of the cathode ray particles, which led to a fascinating discovery, minus the mass of each particle was much, much smaller than that of any known atom. Thomson repeated his experiments using different metals as electrode materials, and found that the properties of the cathode ray remained constant no matter what cathode material they originated from. From this evidence, Thomson made the following conclusions:
The cathode ray is composed of negatively-charged particles.
The particles must exist as part of the atom, since the mass of each particle is only ~1/2000 the mass of a hydrogen atom.
These subatomic particles can be found within atoms of all elements.
While controversial at first, Thomson's discoveries were gradually accepted by scientists. Eventually, his cathode ray particles were given a more familiar name: electrons. The discovery of the electron disproved the part of Dalton's atomic theory that assumed atoms were indivisible. In order to account for the existence of the electrons, an entirely new atomic model was needed.
Explanation:
Normal human sex cells have 23 chromosomes. Use the art to determine the number of chromosomes a sex cell may have if the nondisjuction occured during Meiosis I. Include all possible chromosome totals.
Answer:
46.....................
Which elements are the most reactive and why?
Answer:
Fluorine is identified as the most reactive nonmetal and the most electro-negative element in the periodic table, making it the strongest oxidizing agent. Caesium is the most reactive metal in the periodic table, so much that working with this metal often ends in explosions!
Hydrogen is a very reactive gas, and the alkali metals are even more reactive. In fact, they are the most reactive metals and, along with the elements in group 17, are the most reactive of all elements.
Hope that helps.
how many grams are in 4.5 x 10^22 molecules of water
Answer:
1.35 g
Explanation:
water is h2o, so the molar mass is 1.01x2+16.00=18.02. divide 4.5 x 10^22 by 6.022 x 10^23 to get 7.5 x 10^-2 (2 sig figs). 18.02 x 7.5 x 10^-2 is 1.35 g
Of the following elements, which one has the smallest first ionization energy?
A. boron
B. carbon
C. aluminum
D. silicon
Answer:
C. Aluminum
Explanation:
Aluminum has 5.9858 ionization energy
Boron has 8.298 ionization energy
Silicon has 8.1517 ionization energy
Carbon has 11.2603 ionization energy
how many moles are in 8.32 × × times 10^24 molecules of co2?
Answer:
13.8 moles
Explanation:
You know that in a mole you have 6.022x10²³ something in this case of molecules. By knowing that by each mole you have 6.022x10²³ molecules, then you can establish the factor of conversion:
8.32x10²⁴molec of CO2 x 1 mol/6.022x10²³ molec of CO2
You divide 8.32x10²⁴/6.022x10²³ and you get 13.81 moles.
How many grams of CO2 should be placed in a 250 mL container and -24°C to produce a pressure of 95K PA?
Answer:
About 0.53 g of carbon dioxide needs to be added.
Explanation:
Recall the ideal gas law:
[tex]\displaystyle PV = n RT[/tex]
To determine the amount of carbon dioxide we need, we need to solve for n:
[tex]\displaystyle n = \frac{PV}{RT}[/tex]
Recall that P, V, and T are in atm, L, and K, respectively. R is the universal gas constant.
Convert all values into the correct units:
Volume:
[tex]\displaystyle 250\text{ mL } \cdot \frac{1 \text{ L}}{1000 \text{ mL}} = 0.25 \text{ L}[/tex]
Temperature:
[tex]\displaystyle \begin{aligned} K & =( ^\circ C) + 273.15 \\ \\ & = (-24) + (273.15) \\ \\ & = 249 \text{ K}\end{aligned}[/tex]
And pressure:
[tex]\displaystyle 95 \text{ kPa} \cdot \frac{1.00 \text{ atm}}{101.3 \text{ kPa}} = 0.94 \text{ atm}[/tex]
Substitute and evaluate:
[tex]\displaystyle\begin{aligned} n & = \frac{\left(0.94 \text{ atm}\right)\left(0.25 \text{ L}\right)}{\left(\dfrac{0.08206 \text{ L-atm}}{\text{mol-K}}\right)\left(249\text{ K}\right)} \\ \\ & = 0.012 \text{ mol CO$_2$}\end{aligned}[/tex]
Convert moles to grams:
[tex]\displaystyle 0.012 \text{ mol CO$_2$} \cdot \frac{44.01 \text{ g CO$_2$}}{1 \text{ mol CO$_2$}} = 0.53 \text{ g CO$_2$}[/tex]
In conclusion, about 0.53 g of carbon dioxide needs to be added.
What is the purpose of the chemical ammonia (NH3) in hair dyes?
Answer: Ammonia, an alkaline chemical, is used to raise the pH level (it's levels of acidity) of our hair during the colouring process. This then lifts the cuticles of the hair fibre and allows the colour to be deposited onto the cortex (the inner part of the hair protected by the cuticles). In hair coloring products, ammonium hydroxide is used to support the lightening action of hydrogen peroxide and to prepare hair to accept color pigments. Alkaline properties of ammonia raise the cuticle and allow peroxide and dye molecules to penetrate the hair shaft. (creds to the internet)
Explanation: Hope this helps! :D
what was johann dobereiner contribution to the periodic table
Answer:
he introduced triads of similar chemical properties in periodic table.
Explanation:
Which of the following can be a
wave medium?
A. solids, liquids, gases, and plasma
B. only solids
C. empty space
A quantity of gas has a volume of 250L at 40°C. If the gas is heated to 120°C, what will the new volume be? Which law describes this change?
Answer:
706 L
Explanation:
P1V1 = P2 V2 3 atm 250.0 mL = 1 atm X
T1 T2 290 K 273 K
706 mL = X
Calculate the molar mass for CO
Answer:28.01 grams
Explanation:
What is the source of energy in nuclear weapons?
O A. Combustion
O B. Fusion
O C. Gravity
O D. Fission
Answer:
D. Fission
Explanation:
Induced fission is used to generate nuclear power and for weapons. The products formed during fission gain kinetic energy. It is this energy that is harnessed in nuclear power stations.
12. Draw the dot diagram for a molecule of P2
[show your work and draw a box around your answer]
Explanation:
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[tex]\rule{2000pt}{1000000pt}[/tex]
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Given that the molar mass of NaCl is 58. 44 g/mol, what is the molarity of a solution that contains 87. 75 g of NaCl in 500. ML of solution? Use Molarity equals StartFraction moles of solute over liters of solution EndFraction. 0. 333 M 0. 751 M 1. 50 M 3. 00 M.
Answer:
D
Explanation:
Given that the molar mass of NaCl is 58.44 g/mol, we want to determine the molarity of a solution that contains 87.75 g of NaCl in 500. mL of solution.
Recall that molarity is given by:
[tex]\displaystyle \text{M} = \frac{\text{ mols solute}}{\text{ liters soln.}}[/tex]
Therefore, we can convert the amount of NaCl in the solution to moles of NaCl and the volume from milliliters to liters:
[tex]\displaystyle \begin{aligned} \text{M} & = \frac{(87.75 \text{ g NaCl})}{(500. \text{ mL soln.})} \cdot \frac{1 \text{ mol NaCl}}{58.44 \text{ g NaCl}} \cdot \frac{1000 \text{ mL soln.}}{1 \text{ L soln.}} \\ \\ & = 3.00\text{ } \frac{\text{mol NaCl}}{\text{ L soln.}} \\ \\ & = 3.00 \text{ M} \end{aligned}[/tex]
Hence, our answer is D.
Calculate the density of sulfur dioxide gas (SO2) at 147°C and 29.9 kPa.
The density of the gas is obtained as 0.55 g/L.
We can find the density of the gas using the relation;
PM = dRT
P = pressure of the gas
M = molar mass of the gas
d = density of the gas
R = gas constant
T = temperature
Now;
P = 29.9 kPa
R = 8.314 L·kPa mol·K.
T = 147°C + 273 = 420 K
d = ?
M = 64 g/mol
Substituting values;
d = PM/RT
d = 29.9 kPa × 64 g/mol/ 8.314 L·kPa mol-1K-1 420 K
d = 1913.6/3491.88
d = 0.55 g/L
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2870 j of energy is required to heat and boil one gram of water at 20 °c. how much water at this temperature can 7.14 × 1010 j of energy heat and boil?
Answer:
Explanation:
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The mass of water is equal to 2.48 × 10⁷ g, needs the energy of 7.14 ×10¹⁰ J to heat and boil.
What is the specific heat capacity?The specific heat capacity can be demonstrated as the quantity of energy needed to increase the temperature by one-degree Celcius in one unit of substance.
The temperature will be changed whenever there is a loss or absorption of energy by any substance.
Q = mCΔT
Therefore, there is a direct relationship between the mass of water and the amount of energy.
m ∝ q
[tex]{\displaystyle {\frac{m_1}{m_2} =\frac{q_1}{q_2}[/tex]
[tex]{\displaystyle {m_2} =\frac{q_2}{q_1} \times m_1[/tex]
Given, the energy required to heat mass(m₂) of water, q₂ = 7.14 ×10¹⁰ J
The energy to heat 1 gram of water, q₁ = 2870 J
[tex]{\displaystyle {m_2} =\frac{7.14\times 10^{14}}{2870} \times 1[/tex]
m₂ = 2.48 × 10⁷ g
Therefore, the mass of water is equal to 2.48 × 10⁷ g.
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Which of the following is true of grinding during
digestion?
A. The process of grinding is a physical change
that takes place in the mouth during digestion.
B. The process of grinding is a chemical change
that takes place in the mouth during digestion.
C. The process of grinding is a physical change
that takes place in the small intestine during
digestion
D. The process of grinding is a chemical change
that takes place in the small intestine during
digestion
The process of grinding is a physical change that takes place in the mouth during digestion.
GRINDING:Grinding is one of the processes that occur during the digestion of food molecules into simpler substances.
Grinding of food molecules occurs in the mouth with the aid of the teeth, which is used to chew.
However, the process of grinding is a physical change because it does not result into the formation of new substances or change the chemical constituents of the food.
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A solution containing 0.60 moles of sodium hydroxide is added to excess magnesium sulfate in solution. A white solid, magnesium hydroxide, is formed.
a) Write a balanced equation including the states of reactants and products.
b) write the name of the other product formed?
Explanation:
and then name of the other product will be sodium sulphate
Melting gold with other metals makes 10 karat gold. Which term best describes 10 karat gold
The 10 karat of gold formed by melting gold with other metals is described as homogeneous mixture.
A pure substance is a substance that is made up of only one kind of particle. This type of substance consist of only one element.
A heterogeneous substance is a type of substance that is made up two or more substances existing in different phases.
A homogeneous substance is a type of substance that is made up of two or more substances evenly mixed. This type of substance exist only in one phase.
Thus, the 10 karat of gold formed by melting gold with other metals is described as homogeneous mixture.
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Answer:
homogeneous mixture
Explanation:
I need help ASAP this is my final
Answer:
A
Explanation:
is the best answer...........
Give an example for the neutralisation between a strong acid and a weak base, also mention the nature of its salt.
need help !! ~~~~
Answer:
Neutralization occurs when a strong acid and a strong base come together in a chemical reaction to form water and salt.
Explanation:
not sure huhuhu
What type of energy does a person experience when jumping on a trampoline?
A.) elastic potential
B.)all of these
C.) gravitational potential
D.)kinetic
Answer:
Knetic
Explanation:
When you jump on a trampoline, your body has kinetic energy that changes over time. As you jump up and down, your kinetic energy increases and decreases with your velocity. Your kinetic energy is greatest, just before you hit the trampoline on the way down and when you leave the trampoline surface on the way up.
Please Help giving high points. Perform the following mathematical operation, and eport the answer to the correct number of significant figures. 4568/1.3 = [?]
Answer:
1.3 is the value with the lowest sig figs in your question. So we have 2 sig figs.
4568/1.3 = 3513.84615
Now let's change the answer in sig figs.
We know that trailing zeros don't actually count as part of sig figs.
So we can round the answer to 3500, having the 2 sig figs (3 and 5) while the trailing zeros don't count.
Final answer = 3500
Hurry. NO Spam! Write the neutralization reaction that occurs between HF and LiOH.
Answer:
HF + LiOH = LiF + H2O.
Explanation:
Hydofluoric acid is a weak acid the solution would be slightly basic due to the following equilibrium (condition in the course of a reversible chemical reaction in which no net change in the amounts of reactants and products occurs.)
Hope that helps. x
Which statement below describes the behavior of a Molecules when a substance changes from a gas to liquid
Answer:
As a substance changes from a solid to a liquid to a gas, its molecules first the molecules are moving fast enough, they are able to "escape." They leave the surface of the liquid as gas molecules. Evaporation is not the only process that can change a substance from a liquid to a gas. The same change can occur through boiling.
Explanation:
hopfully this helps!
Given the equation
N2(g) +3H2 (g)--> 2NH3 (g)
1 mole of N2 gas is needed to completely react with 3 moles of H2 gas.
How many molecules of H2 gas are needed?
Answer:
numbers of molecules = 3×6.023×10-23
explain why almunium is often used for long distance over head electric cables (high voltage)
Answer:
because it does not cost much and can be found easily. due to their low resistance and excellent conductivity.
Explanation:
If a car is traveling 100 km/h and comes to a stop in 3 minutes,what is acceleration of a passenger who is using vehicle restraint?
We are given –
Final velocity of car is, v= 0 Initial velocity of car is, u= 100 km/hr Time taken, t is = 3 minutes or 180 secHere–
[tex]\qquad[/tex][tex] \pink{\bf \longrightarrow Initial\: velocity = 100 \:km/hr}[/tex]
[tex]\qquad[/tex][tex] \sf \longrightarrow Initial\: velocity = \dfrac{ 100 \times 1000}{3600} \:m/s[/tex]
[tex]\qquad[/tex][tex]\pink{ \bf \longrightarrow Initial\: velocity = 27.78\: m/s} [/tex]
Now –
[tex]\qquad[/tex]____________________________
[tex]\qquad[/tex][tex] \purple{\bf \longrightarrow Acceleration = \dfrac{Final\: Velocity -Initial \:Velocity }{Time}}[/tex]
[tex]\qquad[/tex][tex] \purple{\bf \longrightarrow Acceleration = \dfrac{v -u}{t}}[/tex]
[tex]\qquad[/tex][tex] \sf \longrightarrow Acceleration = \dfrac{(0- 27.78)}{1800}[/tex]
[tex]\qquad[/tex][tex] \sf \longrightarrow Acceleration =\cancel{ \dfrac{- 27.78}{1800}}[/tex]
[tex]\qquad[/tex][tex] \purple{\bf \longrightarrow Acceleration = -0.015 \: m/s^2} [/tex]
[tex]\qquad[/tex]_______________________________