Answer:
B. materials change their properties.
Explanation:
In a chemical change, materials often change their properties because a re-arrangement of atoms takes place.
A chemical change is one in which new kind of matter is formed.
It is always accompanied by energy changes.
Chemical changes are not reversible. They lead to the production of new kinds of matter It involves mass changesRequires considerable amount of energyFind the Protons and Electrons for nitrogen -3 ion with 7 neutrons.
Answer:
protons: 7; electrons: 10
Explanation:
nitrogen atomic number=# of protons = 7 (doesn't change either in ion or in neutral)
# of electron in neutral N=7
N-3= three electrons are added, thus 7+3=10
You'll be given 100 points if you answer this question!!!!!!!!!!!!
3.
What do we call materials
that let heat pass through
them easily?
Thermal conductors
Thermal insulators
Transparent
4.
Which of these is a good
thermal conductor?
Plastic
Wood
Steel
5.
Which of these is a good
thermal insulator?
Steel
Iron
Polystyrene
6.
To save on heating bills, do
you think the roof of a
building should be lined with
a thermal conductor
a thermal insulator
nothing
7.
How does heat travel?
From cold things to hotter things
From hot things to colder things
Between things of the same temperature
Answer:conducts ,steel, polystyrene, thermal insulation
Explanation:
Calculate how much heat is absorbed by a sample that weighs 12 kilograms, has a specific heat of 0.231 kg/CJ, and is heated from 45 K to 80 K.
PLEASE ANSWER 20 POINTS
Answer:
97 J
Explanation:
Step 1: Given data
Mass of the sample (m): 12 kgSpecific heat capacity (c): 0.231 J/kg.°C (this can also be expressed as 0.231 J/kg.K)Initial temperature: 45 KFinal temperature: 80 KStep 2: Calculate the temperature change
ΔT = 80 K - 45 K = 35 K
Step 3: Calculate the heat required (Q)
We will use the following expression.
Q = c × m × ΔT
Q = 0.231 J/kg.K × 12 kg × 35 K = 97 J
Draw three different Lewis structures that could be possible for ZX2, assuming that Z is the central atom and that X is not hydrogen. Both Z and X obey the octet rule. Give molecular shapes and bond angles for each structure drawn. In each case, use valence shell electron pair repulsion theory to explain why the molecular shape is possible.
Answer:
See images attached and explanation
Explanation:
I have drawn three possible structures of ZX2. We have to remember that the shapes of molecules could be predicted on the basis of the Valence shell electron pair repulsion theory.
The number of electrons on the valence shell of the central atom determines the shape of the molecule. We have also been told that X is not hydrogen.
If the two X atoms are arranged at a bond angle of 180 degrees, we could have either structure I or II. We will have these structures if the Z atom is sp2 hybridized.
Similarly, if the Z atom is sp3 hybridized, we may have structure III in which the molecule is bent with a bond angle less than 109 degrees. This may result from the presence of a lone pair on Z.
Note that all these structures obey the octet rule.
When H2(g) reacts with F2(g) to form HF(g) , 542 kJ of energy are evolved for each mole of H2(g) that reacts. Write a balanced thermochemical equation for the reaction with an energy term in kJ as part of the equation. Note that the answer box for the energy term is case sensitive. Use the SMALLEST INTEGER coefficients possible and put the energy term (including the units) in the last box on the appropriate side of the equation. If a box is not needed, leave it blank.
Answer:
[tex]H_2+F_2\rightarrow 2HF+542 kJ[/tex]
Explanation:
Hello!
In this case, since exothermic reactions evolve or release energy when undergone, we infer that the energy is part of the products as it is a result of the reaction; thus, for the described reaction we should set it up as follows:
[tex]H_2+F_2\rightarrow 2HF+542 kJ[/tex]
However, if the reaction absorbs energy, the energy associated to the reaction is put at the reactants side, keeping in mind that it would be an endothermic reaction.
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A student takes a stock solution that is 50 mM (solute formula weight is 120.5 g/mol) and prepares a series of solutions. The first solution is made by diluting 1 mL of the stock in water to a final volume of 15 mL (sample 1). They then take a 2 mL aliquot of sample 1 and dilute in water to a final volume of 25 mL (sample 2). Finally, they take a 1.5 mL aliquot of sample 2 and dilute to a final volume of 250 mL. Calculate the final molar concentration for the analyte in molarity, molality, ppm, and ppb. State any assumptions.
Answer:
1.6x10⁻⁶M
1.6x10⁻⁶m
0.1928ppm
192.8ppb
Explanation:
The first dilution of the solution is from 1mL to 15mL. The second from 2mL to 25mL and the third from 1.5mL to 250mL. That means molarity is:
50mM =
0.050M * (1mL / 15mL) * (2mL / 25mL) * (1.5mL / 250mL) = 1.6x10⁻⁶M
Molality is defined as the ratio between moles and kg. Assuming the density of the solution is 1kg/L, molality is 1.6x10⁻⁶m
ppm is the ratio between milligrams and Liters:
1.6x10⁻⁶mol / L * (120.5g /mol) * (1000mg / g) = 0.1928mg/L = 0.1928ppm
And ppb = 1000*ppm;
0.1928ppm*1000 = 192.8ppb
PREDICT How do you think the atoms in metal elements are different from those in
nonmetals or metalloids? How might the atoms of different metals vary from one another?
Answer:
See explanation
Explanation:
The atoms of metals have fewer valence electrons than the atoms of metals and metalloids.
Atoms of metals have only very few valence electrons in their outermost shells hence they donate electrons during bonding. However, atoms of nonmetals have more electrons in their outermost shells and rather accept electrons during bonding. The atoms of metalloids just have a number of valence electrons that are intermediate between those of metals and nonmetals and mostly share electrons in covalent bonds.
Similarly, atoms of metallic elements differ from each other in the number of valence electrons present in the valence shell of the atom of each element. For instance, sodium has one electron in the valence shell of its atom while aluminium has three electrons in the valence shell of its atom.
The atoms of metallic elements are different from the atoms of non metals or metalloids base on the outer electron/ valency electrons and the its bonding pattern.
The atoms of different metals varies in it ability to bond quickly.
The atoms of metallic elements are different from the atoms of non metals or metalloids base on the outer electron/ valency electrons and how it bonds.
Metallic atoms have very few electrons in the outermost shell. The valency electrons of this metallic atoms are few and are easily lost during bonding. They have the ability to release there valency electrons easily. Example of this metals are sodium, potassium , calcium etc.
On the other hand non metallic elements have numerous electron in the outermost shell and easily receive electron during bonding. Example are chlorine, fluorine, oxygen etc.
The metalloid atoms like silicon and germanium have an average number of electron in their outermost shell. They are in between.
The atoms of different metals varies in it ability to bond quickly. For example the group 1 metals are very reactive than the group 2 metals. This simply means the group 1 metals(alkali metals) goes into bonding more easily than the group 2 metals(alkali earth metals).
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To save on heating bills, do you think the roof of a building should be lined with
1. a thermal conductor
2. a thermal insulator
3. nothing
Answer:
2. a thermal insulator
Explanation:
To save on heating bills, the roof of a building should be lined with a thermal insulator.
A thermal insulator will help prevent the house from loosing the heat trapped within the house.
An insulator is a substance or device that does not allow for the conduction of heat and electricity. In this problem, an insulator does not allow for heat conduction. A conductor will allow heat pass through readily. So, to trap heat within the house, an insulator is best used.PLZ HELP ASAP WILL GIVE BRAINLISTS TO RIGHT ANSWER
How many molecules of carbon dioxide are in 12.2 L of the gas at STP?
A) 3.28 x 10^23 molecules
B) 5.01 X 10^23 molecules
C)2.24 x 10^23 molecules
D)8.12 x 10^22 molecules
Answer:
c
Explanation:
ok than not c than b maybe
A 250 grams sample of an unknown substance was heated from 35 degree Celsius to 50 degree Celsius. The substance absorbed 7,454 J of energy. What is the specific heat of the substance? Identify if the reaction is exothermic or endothermic
Answer:
Specific heat capacity, c = 1.99J/g°C. The reaction is endothermic because heat is being absorbed.
Explanation:
Given the following data;
Mass = 250g
Original temperature, T1 = 35°C
New temperature, T2 = 50°C
Quantity of heat = 7454J
To find the specific heat capacity;
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.dt = T2 - T1
dt = 50 - 35
dt = 15°C
Making "c" the subject of formula, we have;
[tex] c = \frac {Q}{mdt} [/tex]
Substituting the values into the equation, we have;
[tex] c = \frac {7454}{250*15} [/tex]
[tex] c = \frac {7454}{3750} [/tex]
Specific heat capacity, c = 1.99J/g°C.
Therefore, the reaction is endothermic because heat is being absorbed (initial temperature is lower than the final temperature).
Which of the following is the least important property of a mineral?
A streak
B hardness
C luster
D color
Explanation:
Türküm lben .Türk varmi kardaşlar!!!
Answer:
D color
Explanation:
One physical test for minerals is to check their color. Certain kinds of minerals always have a similar color, but most minerals have a range of colors. This is the least informative property of a mineral. Some words to describe color are: pale, bright, streaked, splotchy, banded, and speckled.
This is from my school assignment good luck everyone!! :D
If the flour mixture is then taken and put into the oven for about 20 minutes, it turns into something very tasty. What kind of change has happened now?
Answer:
physical change
Explanation:
i got the same question sorry for the late response but that's the answer good luck
Which rule states that cracks on glass tend to form at a certain angle on the opposite side of the polnt of Impact?
The
rule states that cracks tend to form at a (n)
angle on the opposite side from the point of Impact.
Answer:
The 3R rule states that cracks tend to form at a (n) right angle on the opposite side from the point of impact.
Explanation:
How many moles are there in 100.0 grams of KMnO4
Answer:
the answer rounded to the nearest hundredth is 0.63
Explanation:
Which of the following BEST describes how these elements would be classified?
A.
Element Q is a nonmetal and element R is a nonmetal.
B.
Element Q is a metal and element R is a metalloid.
C.
Element Q is a nonmetal and element R is a noble gas.
D.
Element Q is a metal and element R is a noble gas.
Draw the electron configuration for a neutral atom of nitrogen.
Answer:
1s22s22p3.
Explanation:
Electronic configuration of a neutral atom is 1s22s22p3.
Please see the image attached
Neutral atom of nitrogen will have equal number of proton and electron i.e equal to 7. 7 electron of the nitrogen are placed into the s and p orbitals in the ground state.
How many F atoms are in this compound? 6MgF2 12 6 8 2
Answer:
5.0×1022 sa taas po yang 22
Write a description of how you know a chemical reaction is occurring.
ANSWER FAST FIRST PERSON GETS BRAINLIEST
Answer:
See explanation
Explanation:
Chemical reactions are also referred to as chemical change. A chemical change often leads to the formation of new substances and is not easily reversible.
A chemical reaction may be accompanied by the emission of heat and light, formation of a precipitate, evolution of gas, or a color change.
These observable physical effects may tell us weather a chemical reaction has taken place or not so we have to observe the system closely for any of these effects stated above.
The heat of vaporization of water at the normal boiling point, 373.2 K, is 40.66 kJ/mol. The molar heat capacity of liquid water is 75.37 J K-1 mol-1 and that of gaseous water is 36.4 J K-1 mol-1. Assume that these values are independent of temperature. What is the heat of vaporization of water at 300.2 K?
Answer:
[tex]\Delta _{vap}H(300.2K)=43,658\frac{J}{mol}=43.66\frac{kJ}{mol}[/tex]
Explanation:
Hello!
In this case, according to the Kirchhoff's law for the enthalpy change, it is possible to compute the heat of vaporization at 300.2 K by considering the following thermodynamic route:
[tex]\Delta _{vap}H(300.2K)=Cp_{liq}(T_b-T\°)+\Delta _{vap}H\°+Cp_{vap}(T-T_B)[/tex]
Whereas the first term stands for the effect of taking the liquid from 298.15 K to 373.15 K, the second term stands for the standard enthalpy of vaporization and the last term that of the vapor from the boiling point to 300.2 K; thus we plug in to obtain:
[tex]\Delta _{vap}H(300.2K)=75.37\frac{J}{mol*K} (373.2K-298.15K)+40,660\frac{J}{mol} +36.4\frac{J}{mol*K}(300.2K-373.2K)\\\\\Delta _{vap}H(300.2K)=43,658\frac{J}{mol}=43.66\frac{kJ}{mol}[/tex]
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PLS HELLPPPP
Which of the following objects would have the greatest gravitational attraction between them if they were set 3.0 km apart?
A .20kg object and a 200kg object
A 10kg object and a 100kg object
A 30kg object and a 200,000kg object
A 400,000 kg object and a 100,000,000kg object
Answer:
A 400,000 kg object and a 100,000,000kg object
Explanation:
The objects with the most mass between them will have the greatest gravitational attraction.
This is why the last option is the right choice.
The reason for this is based on the Newton's law of universal gravitation which states that:
"the gravitational force of attraction between two bodies is directly proportional to the product of their masses and inversely proportional to the square of the distance between them".
So, the more the mass, the greater the gravitational attraction between two bodies.
A chemical reaction takes place inside a flask submerged in a water bath. The water bath contains 6.50kg of water at 24.2°C. During the reaction 88.2kJ of heat flows out of the flask and into the bath.Calculate the new temperature of the water bath. You can assume the specific heat capacity of water under these conditions is 4.18·J·g−1K−1. Be sure your answer has the correct number of significant digits.
Answer:
27.4°C
Explanation:
Using the equation:
Q = m*C*T
Where Q is heat added,
m the mass of water
C specific heat of water (4.18J/g°C)
And T the increase in temperature
We can solve for the increase in temperature and thus, the final temperature of water:
Q = 88200J; m = 6500g:
88200J = 6500g*4.18J/g°C*T
3.2°C = T = increase in temperature
Final temperature is:
24.2°C + 3.2°C =
27.4°CWhich is the closest antonym for the word enhance?
A prolong
guarantee
C
diminish
salvage
Answer:
C. Diminish.
Explanation:
An antonym is the opposite meaning of a given word. It is the word that gives the complete opposite meaning of the given word.
The word "enhance" means "to increase, intensify, magnify, to make it more than it already is" etc. So, the antonym of that word will be "to diminish, to reduce, to prevent" etc.
Thus, the correct answer is option C.
Plz help ASAP i will give brainlists
2AgNO3 + BaCl2 + 2AgCl + Ba(NO3)2
How many grams of silver chloride are produced from 15.0 g of silver nitrate reacting with an excess of barium chloride?
A)9.44 g Agci
B)16.4 g Agci
C)12.7 g Agci
D)0 20.1 g Agci
Suppose a 500.mL flask is filled with 0.40mol of N2 and 1.0mol of NO. The following reaction becomes possible:
N2g+O2g ->2NOg
The equilibrium constant K for this reaction is 5.93 at the temperature of the flask. Calculate the equilibrium molarity of N2. Round your answer to two decimal places.
Answer:
[N₂] = 1.1M
Explanation:
Based on the chemical reaction:
N₂(g) + O₂(g) ⇄ 2 NO(g)
Equilibrium constant, K, is defined as:
K = 5.93 = [NO]² / [N₂] [O₂]
Where [] are equilibrium concentrations of each specie
As initial concentrations are:
N₂ = 0.40mol / 0.500L = 0.8M
NO = 1mol / 0.500L = 2M
The equilbrium concentrations are:
[NO] = 2M - 2X
[N₂] = 0.8M +X
[O₂] = X
Replacing:
5.93 = [2 - 2X]² / [0.8+X] [X]
5.93 = 4 - 8X + 4X² / 0.8X + X²
4.744X + 5.93X² = 4 - 8X + 4X²
1.93X² + 12.744X - 4 = 0
Solving for X:
X = -6.9M → False solution. There are no negative concentrations
X = 0.3M. Real solution.
[N₂] in equilibrium is:
[N₂] = 0.8M +0.3M
[N₂] = 1.1M
[10 pts]Iron and vanadium both have the BCC crystal structure and V forms a substitutional solid solution in Fe for concentrations up to approximately 20 wt.% V at room temperature. Determine the concentration in weight percent of V that must be added to iron to yield a unit cell edge length of 0.289 nm.
Answer:
The answer is below
Explanation:
The unit cell edge length (a) = 0.298 nm = 0.289 * 10⁻⁷ cm
The unit volume (V) = a³ = (0.289 * 10⁻⁷ cm)³ = 24 * 10⁻²⁴ cm³
There are 2 atoms per cell, hence N = 2. Also, [tex]n_a=avogadro\ constant=6.02*10^{23}\ mol^{-1}[/tex]
[tex]atomic\ weight\ of\ iron(A_f)=55.85,atomic\ weight\ of\ vanadium(A_V)=50.94,[/tex]
[tex]density\ of\ iron(\rho_f)=7.87,density\ of\ vanadium(\rho_v)=6.1.\\\\V=\frac{nA_{av}}{n_a\rho_{av}} \\\\A_{av}=\frac{100}{C_v/A_v+C_f/A_f} \\\\\rho_{av}=\frac{100}{C_v/\rho_v+C_f/\rho_f} \\\\C_v=concentration\ of\ vanadium,C_f=concentration\ of\ iron.\\\\V=\frac{nA_{av}}{n_a\rho_{av}}=\frac{n*\frac{100}{C_v/A_v+C_f/A_f}}{n_a*\frac{100}{C_v/\rho_v+C_f/\rho_f}}\\\\[/tex]
[tex]24*10^{-24}=\frac{2*\frac{100}{C_v/50.94+C_f/55.85}}{6.02*10^{23}*\frac{100}{C_v/6.1+C_f/7.87}}\\\\7.2=\frac{C_v/6.1+C_f/7.87}{C_v/50.94+C_f/55.85}\ \ \ (1) \\\\Also:\\\\C_v+C_f=100\%\ \ \ (2)\\\\\\solving\ equation\ 1\ and\ 2\ simultaneously\ gives:\\\\C_v=10\% \ and\ C_f=90\%\\\\[/tex]
helppp nowww plsss rnnn!
______ is required for making a scientific inquiry
Analyze: What pattern do you see? Make a rule: Based on your data, how are elements arranged into chemical families?
Answer: in order of increasing atomic number.
Explanation: Elements in the same group have similar chemical properties. This is because they have the same number of outer electrons and the same valency.
Answer:
What pattern do you see?
Chemical families have the same number of valence electrons.
Make a rule: Based on your data, how are elements arranged into chemical families?
They are arranged vertically depending on how many valence electrons they have, if they have the same amount, they will have the same chemical family in each column.
Calculate the number of oxygen atoms in a 50.0g sample of scheelite CaWO4
Answer:
0.696 atoms of oxygen
Explanation:
We'll begin by calculating the number of mole in 50 g of scheelite CaWO₄. This can be obtained as follow:
Mass of CaWO₄ = 50 g
Molar mass of CaWO₄ = 40 + 184 + (4×16)
= 40 + 184 + 64
= 288 g/mol
Mole of CaWO₄ =?
Mole = mass / Molar mass
Mole of CaWO₄ = 50 / 288
Mole of CaWO₄ = 0.174 mole
Finally, we shall determine the number of oxygen atom in 50 g (i.e 0.174 mole) of CaWO₄. This can be obtained as follow:
1 mole of CaWO₄ contains 4 atoms of oxygen.
Therefore, 0.174 mole of CaWO₄ will contain = 0.696 atoms of oxygen.
Thus, 50 g (i.e 0.174 mole) of CaWO₄ contains 0.696 atoms of oxygen.
Which is an example of maintaining structure?
Question 4 options:
healing a wound
sweating
all answers are examples of maintaining structure
keep from getting too cold
Answer: healing a wound
Explanation:
The healing of the wound is the example of maintenance of the structure. The wound is the injury which disturbs the continuity of the skin surface. It can affect the dermal and epidermal layer of the skin. The wound if severe or deep can damage the bones. The wound can be caused by the cut, blow or punch, impact or fall from height. The healing of the wound may take several days to weeks. The wound healing involves the replacement of the damaged or destroyed cells or tissues by new cells or tissues in the body or the wound site.