Avogadro's law states that in every mole of a substance, there are [tex]6.022 \times 10^{23}[/tex] molecules.
This means that in 2.3 moles, there are [tex]2.3(6.022 \times 10^{23})=\boxed{1.4 \times 10^{24} \text{ (to 2 sf)}}[/tex]
which of these changes are endothermic and which are exothermic
baking a cake
bending a plastic ruler
cutting paper
melting ice cream
ripening of fruit
souring of milk
Answer:
exothermic - bending a plastic ruler , cutting paper, melting ice cream, ripening of fruit, souring of milk.
Explanation:
endothermic- baking of cake .
How many individual Ni atoms are contained in 1.25 grams of Ni? (Input your answer with scientific notation using "e-notation" and report your answer to two places past the decimal point.
Answer:
Ni atoms are contained in 1.25gram is 1.28e22 atoms.
Explanation:
Ni atoms are contained in 1.25gram is 1.28e22 atoms.
We have a Nickel(Ni) atom . The atomic number of Ni is 28 .It is a silvery-white metal with a slight golden tinge. Ni belongs to the transitional metal series.
The electronic configuration of Ni = Ar4d⁸35²
Nickel is slowly oxidized by air at room temperature.
Nickel is a ferromagnetic element at approximately room temperature.
To answer the problem , we first need to divide by the molar mass of Ni to get the moles of Ni. And then we will multiply by Avogadro's number to find the number of Ni atoms.
Molar mass of Ni = 58.7gm
Given mass of Ni = 1.25gm
Avogadro’s No. = 6.022 × 10²³ atom/mole
Moles of Ni = Given mass/Molecular mass
= 1.25/58.7 = 0.0213
Moles of Ni = 0.0213
Now ,
Number of Ni atom = Avogadro’s number × Moles
So that,
No. of Ni atom = 6.022 × 10²³× 0.0213
= 0.128 ×10²³ atoms
= 1.28 × 10²² atoms
= 1.28e22
So there are 1.28 × 10²² individual Ni atoms are contained in 1.25 grams of Ni.
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Please answer one question. thanks so much if u do
What is the substance produced by a chemical reaction called?
a) Reactant
b) Product
c) Resultant
d) Reagent
e) Summation
What kind of chemical reaction involves oxygen and another substance producing water and carbon dioxide?
a) Synthesis reaction
b) Decomposition reaction
c) Combustion
d) Single displacement
e) Photochemical reaction
What does a catalyst do to a chemical reaction?
a) Stops the reaction
b) Starts the reaction
c) Speeds up the rate of reaction
d) Slows down the rate of reaction
e) None of the Above
Answer:
b) Product
c) Combustion
c) speeds up the rate of reaction
Explanation:
the substance produced by a chemical reaction is called a product (b)
Combustion (c) reactions are involving oxygen and "another substance" [and hydrocarbons] to produce carbon dioxide and water.
A catalyst acts to speed up the rate of a reaction (c)
> note how it "speeds up" reaction: , it [a catalyst] lowers the pressure or temperature needed to start one--but it isn't used/consumed in the reaction
So, the answers are: b, c, c
hope this helps!!
A box has dimensions of 2.5 cm by 3.0 cm by 4.0 cm. The volume of the box in milliliters and liters is Group of answer choices 3,000 mL and 3.0 L 30 mL and 30,000 L 7.5 mL and 7,500 L 30 mL and 0.030 L 7.5 mL and 0.0075 L
Considering the definition of volume, the volume of the box is 30 mL or 0.03 L.
What is volumeVolume is a metric magnitude that is defined as the extension in three dimensions of a region of space. In other words, it is defined as the amount of space occupied by the object or figure in three-dimensional space. Volume is measured in cubic units.
Volume can be considered as the capacity of a container to hold a quantity of fluid (gas or liquid).
Volume of a boxA box is a rectangular prism, which is defined as a prism with rectangular bases and rectangular lateral faces.
The volume of this prism depends on its three dimensions and is calculated as the multiplication of these dimensions:
Volume= Dimension 1× Dimension 2× Dimension 3
Volume of the box in this caseIn this case, you know that a box has dimensions of 2.5 cm by 3.0 cm by 4.0 cm. So, the volume can be calculated as:
Volume= 2.5 cm× 3 cm× 4 cm
Solving:
Volume= 30 cm³
Being 1 cm³= 1 mL and 1 L= 1,000 mL then:
Volume= 30 cm³= 30 mL= 0.03 L
Finally, the volume of the box is 30 mL or 0.03 L.
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What causes ionic bonding between two atoms?
Answer:
Ionic bonding happens when an atom of an element gives one or more of its electrons to the other element's atom..it usually takes place between metal and non metal atoms...like in NaCl, Na gives its valence electron to chlorine and completes its own octet. Chlorine accepts the electron and completes its own octet too...but now both the atoms have an opposing charge and hence they attract each other to form an IONIC bond.
Ionic bonds are the strongest of the bonds...here complete transfer of electrons takes place unlike covalent bonds.
HOPE IT HELPED..
:)
Answer:
The electrostatic interaction between an anion and cation
Use the periodic table to answer the questions below.
Which diagram shows the correct electron
configuration for nitrogen (N)?
N N N1
1s
2s
2p
NN ILL
1s 2s
2p
N N
1s
2s
DONE✔
2p
The diagram that show the correct electron configuration is the second option. ⬆⬇1s, ⬆⬇2s, ⬆⬆⬆2p.
What is electronic configuration?The electronic configuration is the representation of electron present indifferent energy levels is an atom. The different type of orbitals are s, p, d, and f.
Thus, the correct option is 2, ⬆⬇1s, ⬆⬇2s, ⬆⬆⬆2p.
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What does viscosity describe
work out the size of resistance.
Answer:
Step 1: Identify the resistivity (ρ) , length (L), and radius (r) of the wire. Step 2: Calculate the cross-sectional area of the wire using the formula for the area of a circle: A=πr2 A = π r 2 . Step 3: Calculate the resistance (R) of the wire using the formula for resistance: R=ρLA R = ρ L A
What is the mass in grams of 4.85 x 10^22 Al atoms? (Report your answer to two places past the decimal
Answer:
2.17 gm Al
Explanation:
First, find the number of moles . Then multiply by the mole weight of aluminum.
# moles = 4.85 x 10^22 / 6.022 x 10^23 = .08053 moles
.0805 moles * 26.981 gm/mole = 2.173 gm
can see all wavelengths/photons of light emitted from excited electrons.
No, all wavelengths/photons of light are emitted from excited electrons.
What is wavelength?Wavelength is the distance between identical points (adjacent crests) in the adjacent cycles of a waveform signal propagated in space or along a wire.
When an atom's electrons move to a lower energy state, the atom releases energy in the form of a photon. Depending on the energy involved in the emission process, this photon may or may not occur in the visible range of the electromagnetic spectrum.
Hence, no, all wavelengths/photons of light are emitted from excited electrons.
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Two samples contain sulfur and
oxygen in the amounts shown in the
data table. What is the mass percent
of sulfur in compound B?
Sample Mass S (g) Mass 0 (g)
A
32.0
48.0
B
30.0
30.0
Answer:
Sample A=40 Sample B=50
Explanation:
32+48=80
32/80x100=40
The 100 is to convert it to a percentage
___________________________
Sample B
same thing
30+30=60
30/60x100=50
The mass percent of sulfur in compound B is 50 %
What is mass percent?Mass percent is defined as a way of expressing a concentration or describing the component in a particular mixture.
It can also be defined as a mass of a element or solute divided by the mass of compound or solvent.
Mass percent of sulfur of sample A
= 32 + 48 = 80
= 32 / 80 x 100
= 40 %
Mass percent of sulfur of sample B
= 30 + 30 = 60
= 30 / 60 X 100
= 50 %
Thus, the mass percent of sulfur in compound B is 50 %
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Which statement best describes how the scientific community analyzes data?
OA. A scientist must always keep his or her data hidden from other
scientists.
B. There is only one possible conclusion to be drawn from a set of
data.
OC. Each scientist must use his or her own, unique data.
OD. Scientists can come to different conclusions based on the same
data.
SUBMIT
Answer: D. Scientists can come to different conclusions based on the same data.
Discuss how varying ph of water affects the soil ph which in turn would affect the durability properties of reinforced concrete as a constituent material?
Although soils are capable of resisting pH changes, there are some circumstances where the pH of the water can result in alterations.
Will Soil pH Be Affected by Water pH?The texture of soil affects how susceptible it is to the pH of the surrounding water. Smaller soil particles, such as clays and clay loams, have a greater impact than larger, sandier soils. There are more colloids, which are extremely minute particles, in fine-textured soils. Positively charged ions are maintained at these colloids. The cation exchange capacity of a soil refers to its capacity to hold onto these ions. Ions on the colloidal particles trade places with ions in the soil solution. The pH of the soil is less affected by negative ions in the soil solution.
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A graduated cylinder is filled to 12.5 mL
with water and a piece of tin is placed
in the cylinder, displacing the level to
16.8 mL.
What is the volume of the tin piece in
cubic centimeters?
[?] cm³
Record your answer to the tenths place.
Volume (cm³)
The volume of the tin piece in cubic centimetres is 4.3 cm³
What is a graduated cylinder?A graduated cylinder is a standard piece of laboratory glassware used to measure the volume of an object or amount of liquid. As its name indicates, it is a glass cylinder with marks along the side similar to those on a measuring cup.
When adding an object to a liquid, the displayed volume difference corresponds to the volume of the added object.
In this way, to find the value of the object's volume, subtract the initial volume from the final volume:
16.8ml - 12.5ml = 4.3ml
To convert to cubic centimetres, the conversion scale of volume and length measurements need to be used, finding that mL is equal to cubic centimetres. So, the final answer is:
4.3 cm³
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Which would be a good use for an organic substance? Check all that apply. A. Electrical conductors B. Waterproof coatings C. Fuels such as gasoline D. Microchips E. Plastic storage containers
Answer:
B. waterproof coatingExplanation:
please mark me brainlistGIVING 17 POINTS PLS HELP ME!!!!
Which of the following statements is true about hydropower?
A. It releases carbon dioxide.
B. It can produce harmful chemicals.
C. It can affect fish and other marine life.
D. It uses gas trapped under Earth's surface.
Hydropower can affect fish and other marine life which is the true statement and is denoted as option C.
What is Hydropower?
This is the process in which water energy is converted into electrical energy through the use of dams and turbines.
When the dams are created, it blocks the path of marine activities and limits them to certain activities such as reproduction.
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50 atoms, 15 were isotope A, 30 were isotope B, and 5 were isotope C, which isotope would be the most abundant?
The most abundant isotope among the given Isotopes will be Isotope B
How to calculate percentage abundance of isotopes ?To calculate the percent abundance of each isotope in a sample of an element, we usually divide the number of atoms of a particular isotope by the total number of atoms of all isotopes of that element and then multiply the result by 100.
For Isotope A ;% Abundance = 15/50 x 100
= 30 %
For Isotope B ;% Abundance = 30/50 x 100
= 60 %
For Isotope A ;% Abundance = 5/50 x 100
= 10 %
Hence, The most abundant isotope among the given Isotopes will be Isotope B.
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How many liters of a 0.80 M
solution can be made with 2.0 mol
KNO3?
Answer: 2.5
Explanation: you devide mol solute which is 2.0 and the L solution which is 0.80M, and after you divide the two you get 2.5
i also had this question <3
The molarity is an important method to calculate the concentration of a solution. The volume of potassium nitrate of 0.80 molarity and 2.0 mol moles is 2.5 L.
What is molarity?The molarity of a solution is defined as the number of moles of the solute present per litre of the solution. It is mainly employed in calculating the molarity of a binary solution. It is represented as 'M' and unit is mol L⁻¹.
The equation used to calculate the molarity is given as:
Molarity = Number of moles of the solute / Volume of the solution in litres
Here molarity = 0.80 M
Number of moles = 2.0 mol
Then the volume of the solution = Number of moles of the solute / Molarity
Volume = 2.0 / 0.80 = 2.5 L
Thus the volume of the solution is 2.5 L.
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The molecular structure of water has an asymmetrical arrangement of hydrogen atoms causing.
Answer:
the asymmetrical arrangement of hydrogen atoms in a molecule of water causes the molecule to be polar, with the hydrogen atoms having a slightly positive charge, and the oxygen atom having a slightly negative charge.
which type of scientist would most likely study how the size of the lemming population affects the size of the snowy owl population?
A. A biologist
B. A sociologist
C. A chemist
D. A physicist
HELP PLS
The type of scientist would most likely study how the size of the lemming population affects the size of the snowy owl population is a biologist.Thus, the correct option is (D)
What Biologist does ?
Biologists study humans, plants, animals, and the environments in which they live.
They may conduct their studies--human medical research, plant research, animal research, environmental system research--at the cellular level or the ecosystem level or anywhere in between.
Hence, The type of scientist would most likely study how the size of the lemming population affects the size of the snowy owl population is a biologist.Thus, the correct option is (D)
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An ice freezer behind a restaurant has a freon leak, releasing 31.68 g of C2H2F3Cl into the air every week. If the leak is not fixed, how many kilograms of fluorine will be released into the air over 6 months
The weight of fluorine released in to the air over 6 month will be 0.365 kg
What is Freon ?
Freon is a non-combustible gas that is used as a refrigerant in air conditioning applications.
This freon undergoes an evaporation process over and over again to help produce cool air that can be circulated throughout your AC system
Total number of weeks = 6 x 4 = 24
Mass leak rate of freon = 31.68 g/week
Mass leak rate of flourine = fluorine mass in freon / molecular mass of freon x leak rate
= 19 x 3 / 118.5 x 31.68
= 15.23 gm/week
Total fluorine leak in 6 month = 15.23 x 24 = 365.72 gm = 0.365 kg
Hence, The weight of fluorine released in to the air over 6 month will be 0.365 kg
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Arrange these elements into a table showing metals and non-metals: phosphorus, P, barium, Ba, vanadium, V. mercury, Hg, krypton, Kr, potassium, K, and uranium, U.
...,...................................
Which statement best describes how changing the temperature of a solution
affects the rate of reaction?
A. Increasing the temperature of a solution increases the
concentration of the reactants.
B. Decreasing the temperature of a solution increases the rate of
reaction.
C. Increasing the temperature of a solution increases the rate of
reaction.
D. Decreasing the temperature of a solution increases the
concentration of the reactants.
Scientists used alpha particles to investigate models of the atom. Figure 4 shows an alpha particle scattering experiment.
Explain how scientists used the results from the experiment to :
disprove the plum pudding model
give evidence for the new nuclear model
Answer:
See attached image.
Explanation:
If 1.32 g MgO is combined with 100.0 mL of 1.00 M HCl in a coffee cup calorimeter, the temperature of the HCl solution increases from 24.2 °C to 34.4 °C. Calculate the enthalpy change for the reaction per mole of MgO. Assume that the specific heat of the HCl solution is 4.18 J/g·°C and its density is 1.00 g/mL.
MgO(s) + 2HCl (aq) MgCl2 (aq) + H2O (l)
The change in enthalpy for the reaction per mole is -130KJ/mol.
Given,
Reaction: MgO(s) + 2HCl (aq) →MgCl₂ (aq) + H₂O (l)
1.32 g MgO is combined with 100.0 mL of 1.00 M HCl in the cup of coffee.
Change in temperature, ΔT=34.4 °C-24.2 °C =10.2°C
Specific heat of the HCl solution, c= 4.18 J/g·°C
Density= 1.00 g/mL
Mass can be written as the product of density and volume.
Mass= Density × Volume= 1g/ml × 100 ml=100g
Heat can be written as
Heat, Q=mcΔT=100g×4.18 J/g·°C×10.2°C=4263.6J
Number of moles of the MgO,
n= (mass of MgO)/(Molar mass)= 1.32g/(40.3g/mol)= 0.03275 mol
Change in Enthalpy, ΔH=-Q/(n)=(-4263.6J)/(0.03275 mol)
ΔH= -1300186J/mol= -130KJ/mol
Hence, the change in enthalpy for the reaction per mole is -130KJ/mol.
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Does this equation show that transmutation has taken place during decay? why or why not?
61/28 ni=61/28 ni + y
a. yes, because the numbers of nucleons and atoms are conserved
b. no, because high-energy electromagnetic waves are emitted
c. no, because there is conservation of the number of atoms as well as the number of nucleons
d. yes, because nickel atoms remain nickel atoms with the same number of neutrons
The equation is not a transmutation because there is conservation of the number of atoms as well as the number of nucleons; option C.
What is transmutation?Transmutation refers to the artificial synthesis of new elements by a nuclear reaction of the original element and nuclear particles.
In transmutation, a new element is formed and the atomic number changes.
Based on the above, it can be concluded that the given equation is not a transmutation because there is no change in atomic and nucleon number.
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How many liters of a 0.80 M
solution can be made with 2.0 mol
KNO3?
{?} L
Answer:
Explanation:
Solution
Verified by Toppr
2 molL
−1
Explanation :
Concentration =
Volume of solution
Moles of solute
We assume that potassium nitrate dissolves in the given volume of solvent without gross change in volume.
Concentration =
101.10gmol
−1
404g
Write the half reaction equations at the cathode and anode
A redox reaction is one in which oxidation and reduction occurs.
What is a redox reaction?A redox reaction is one in which oxidation and reduction occurs. Oxidation involves electron loss while reduction involves electron gain.
For the compound NaI;
The oxidation half equation is - 2Na(s) --->2Na^+(aq) + 2e
The reduction half equation is - I2 + 2e ---->2 I^-(aq)
Missing parts:
Write the anode half-reaction and cathode half-reaction for NaI.
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Which of the following is a double replacement reaction?
K2S + CoCI2 -> 2KCI + CoS
Ca + 2H2O -> Ca (OH)2 + H2
CaO + H2O -> Ca(OH)2
2KCIO3 -> 2KCI + 3O2
The reaction that exemplifies a double replacement reaction is as follows: K2S + CoCI2 -> 2KCI + CoS, which is option 1.
What is a double replacement reaction?A double replacement reaction is a type of reaction in which two elements are substituted in the reacting compounds.
In the reaction given as follows:
K2S + CoCI2 -> 2KCI + CoS
Pottasium replaces cobalt in Cobalt chlorideSulfur replaces chlorine in Cobalt chlorideTherefore, the reaction is a type of double replacement reaction.
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How do you test for hydrogen?
To test for hydrogen, burn a candle near the suspected source of hydrogen. If you hear a squeaky pop sound, hydrogen is present because when hydrogen gas burns, it makes a squeaky pop sound.
Hydrogen burns with a loud pop in when a burning splint is held near it.
Test for hydrogenThere are a couple of ways to test for hydrogen. However, the simplest and most popular way is to bring a burning splint near a container containing hydrogen gas.
The production of a loud squeaky pop sound indicates the presence of hydrogen gas. All precautions should, however, be observed.
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