When a material gains thermal energy and melts, it is undergoing a physical change.
Answer:
True, it undergoes a physical change.
Explanation:
A physical change is a change that does not change the chemical makeup of a material. This includes altering its shape.
A 7.28 g sample of chromium metal was heated to produce chromium oxide. The weight of the compound was 10.63 g. What is the percent chromium in this compound?
Answer:
68.48%
Explanation:
The percent mass of an element in a compound tells us about the amount of such element contributed to the total compound.
In this case, 7.28 g sample of chromium metal was heated to produce chromium oxide with weight of 10.63 g. The percent mass of chromium in chromium oxide can be calculated by using the formula:
%mass of Cr = mass of Cr/mass of Chromium oxide × 100%
%mass of Cr = 7.28/10.63 × 100
%mass of Cr = 0.6848 × 100
%mass of Cr = 68.48%
Describe how simple distillation is used to separate water from an aqueous solution of sodium
sulfate.
Answer:
hbyiy
Explanation:
A neutral atom becomes a positive ion when it
Answer:
Neutral atoms can be turned into positively charged ions by removing one or more electrons.
Explanation:
If there is an atom that has 9 protons and 9 electrons, removing an electron from the atom will gain a postive charge.
Whenever the same two elements form more than one
compound, the different masses of one element that combine
with the same mass of the other element are in the ratio of
small whole numbers.
TRUE
FALSE
Answer:
The answer is true
Explanation: Because The law of multiple proportions states that when two elements react to form more than one compound, a fixed mass of one element will react with masses of the other element in a ratio of small, whole numbers.
Which one of the following is NOT a proper unit for frequency? *
m·s–1
Hz
s–1
1/s
Answer:
m*s⁻¹.
Explanation:
Hello!
In this case, since the frequency measures how repetitive an event is per unit of time, for instance the laps a car drives every 5 minutes or something similar, we can infer it has units of event/time; in such a way, the unit m*s⁻¹ is not a proper unit of frequency because it is a proper unit of velocity which is the distance traveled per unit of time.
In such a way, Hz (hertz), s⁻¹ and 1/s are possible ways frequency can be represented.
Best regards!
List 5 foods that contain bacteria?
A 12 gram piece of Cu at 475 oC is placed in contact with a 15 gram piece of Cr at 265 oC.
Assume the two pieces of metal are the system and that there is no heat exchange between system and surrounding.
What is the final temperature of the two pieces of metal expressed in degree C?
Answer:
349.22°C
Explanation:
Let the final temperature of the two pieces of metal be x.
Now, the warmer metal which is C u reduces from 475°C to x. Thus Δt for C u is; Δt1 = 475 - x.
The cooler metal Cr increases in temperature from 265°C to x. Thus, it's change in temperature is Δt for Cr is; Δt2 = x - 265.
Now from conservation of energy, the amount of energy leaving the C u metal is equal to the amount of energy entering the Cr metal.
Thus;
q_lost = q_gain
Where;
q_lost = m1•c1•Δt1
q_gained = m2•c2•Δt2
Now, c1 & c2 are the specific heat capacity of C u and Cr respectively.
From online tables, c1 = 0.385 J/g°C and c2 = 0.46 J/g°C
We are given;
m1 = 12g and m2 = 15g
Thus;
12 × 0.385 × (475 - x) = 15 × 0.46 × (x - 265)
2194.5 - 4.62x = 6.9x - 1828.5
6.9x + 4.62x = 2194.5 + 1828.5
11.52x = 4023
x = 4023/11.52
x = 349.22°C
PLEASE HELP ME!!!!!!!!!!!!!!!!!!!
WRITE A SHORT PASSAGE ON HOW FIBRES ARE SPUN
HELPPP WILL MARK AS BRAINLIEST
Answer: Spun yarn is made by twisting staple fibers together
To make a cohesive thread Or “single”. Twisting fibers, into yarn in the process called spinning can be dated back to the upper Paleolithic. Yarn spinning was one of the first processes to be industrialized.
Explanation:
The atomic masses of 20Ne (90.48 percent), 21Ne (0.27 percent), and 22Ne (9.25 percent) are 19.9924356, 20.9938428, and 21.9913831 amu, respectively. Calculate the average atomic mass of neon. The percentages in parentheses denote the relative abundance
Answer:
20.180042 amu
Explanation:
From the question given above, the following data were obtained:
Isotope A (20Ne)
Mass of A = 19.9924356 amu
Abundance (A%) = 90.48%
Isotope B (21Ne):
Mass of B = 20.9938428 amu
Abundance (B%) = 0.27%
Isotope C (22Ne):
Mass of C = 21.9913831 amu
Abundance (C%) = 9.25%
Average atomic mass of Neon =.?
The average atomic mass of Neon can be obtained as follow:
Average atomic mass = [(mass of A × A%)/100] + [(mass of B × B%)/100] + [(mass of C × C%)/100]
= [(19.9924356 × 90.48)/100] + [(20.9938428 × 0.27) /100] + [(21.9913831 × 9.25) /100]
= 18.0891557 + 0.05668338 + 2.03420294
= 20.180042 amu
Therefore, the average atomic mass of Neon is 20.180042 amu
Predict and write the charges and symbols of the monatomic ions formed by the following atoms: bromine rubidium
Answer: The monoatomic ions formed by bromine and rubidium are [tex]Br^-[/tex] and [tex]Rb^+[/tex] respectively.
Explanation:
When an atom accepts an electron negative charge is created on atom and is called as anion. When atom loses an electron positive charge is created on atom and is called as cation.
The atomic number of bromine and rubidium is 35 and 37 respectively. So, the number of electrons is equal to 35 and 37 respectively. Bromine will gain one electron and rubidium will lose one electron to attain stable electronic configuration to form [tex]Br^-[/tex] and [tex]Rb^+[/tex] respectively.
[tex]Br:35:1s^22s^22p^63s^23p^64s^23d^{10}4p^5[/tex]
[tex]Br^-:36:1s^22s^22p^63s^23p^64s^23d^{10}4p^6[/tex]
[tex]Rb:37:1s^22s^22p^63s^23p^64s^23d^{10}4p^63s^1[/tex]
[tex]Rb^+:36:1s^22s^22p^63s^23p^64s^23d^{10}4p^6[/tex]
I need the answer multiple choice
Answer:
it's answer is
element of an atom ✌️
7) If the mass of an object is 20 g and its volume is 25 L. What is the density of this object? 1 8) What is the difference between accuracy and precision? Copy and paste a picture of something that accurate but not precise and also something that is precise, but not accurate. 9) What is the formula for percent error?
this is due under 30 mins, please help
Answer:
Accuracy is the closeness of a measured value to the accepted or exact value. The precision of a tool is the smallest unit of measure the tool provides. The smaller the units a tool can measure, the more precise the tool. A measurement can be precise and not be accurate.
Explanation:
A Barometer reads 29.1 inches of mercury.Calculate this pressure in mmHg.
What is the answer?
This follows a simple conversion technique. Basically what the question is trying to say here is to convert 29.1 inHg to mmHg. 1 inHg is equal to 25.4 mmHg so 29.1 inHg would be equal to [tex]25.4 * 29.1[/tex] which when evaluated turns out to be: [tex]739.14[/tex]. :D
The pressure will be 739.14 mm Hg.
What is pressure?The SI unit measuring pressure would be the pascal, which measures the force of each unit area of the surface.
Calculation of pressure
It is known that 1inHg = 25.4 mm Hg.
Hence, the pressure = 25.4 × 29.1 = 739.14 mm Hg
Therefore, the pressure will be 739.14 mm Hg.
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every spring has an equilibrium position which statement describe a spring at it equilibruim position?
HELP
What type of bond is formed between the carbon and either oxygen in CO2?
A) Single
B) Double
C) Triple
Will give brainliest, Look at the graph above. Compare it to the periodic table. What do you notice about the location on the periodic table of the elements that represent the high points
Answer:
We can see that the atomic radius decreases across every row.
Explanation:
I will comment more below.
The elements that represent the highest points on the graph are all elements of group 1 and occur at the head of the period to which they belong.
The periodic table is an arrangement of elements in groups and periods. The elements in the same group have the same number of valence electrons while the elements in the same period have the same number of shells.
Looking at the graph, we can see that the high points in the graph all correspond to the group 1 elements; sodium, potassium, rubidium and cesium.The have the highest atomic radii in the period. Atomic radii increases down the group but decreases across the period. Remember that these elements are at the head of the period to which they belong hence they have the highest atomic radii.
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Why does the flask have to be closed during the hydrochloric acid and sodium carbonate reaction?
Answer:
The flask has to be closed during the hydrochloric acid and sodium carbonate reaction as the resultant gas got trapped inside the closed flask.
Explanation:
The hydrochloric acid and sodium carbonate reaction was exothermic that caused the pressure to decrease. The flask has to be closed during the hydrochloric acid and sodium carbonate reaction as the resultant gas got trapped inside the closed flask.
In exothermic reactions, energy is produced in the form of heat or light.
An excess of oxygen reacts with 451.4 g of lead, forming 374.7 g of lead(II) oxide. Calculate the percent yield of the reaction.
Answer: The percent yield of the reaction is 77.0 %
Explanation:
[tex]2Pb+O_2\rightarrow 2PbO[/tex]
[tex]\text{Number of moles}=\frac{\text{Given mass}}{\text{Molar mass}}[/tex]
[tex]\text{Number of moles of lead}=\frac{451.4g}{207.2g/mol}=2.18moles[/tex]
[tex]\text{Number of moles of lead oxide}=\frac{374.7g}{223.2g/mol}=1.68moles[/tex]
According to stoichiometry:
2 moles of [tex]Pb[/tex] produces = 2 moles of [tex]PbO_2[/tex]
2.18 moles of [tex]Pb[/tex] is produced by=[tex]\frac{2}{2}\times 2.18=2.18moles[/tex] of [tex]PbO_2[/tex]
Mass of [tex]PbO_2[/tex] =[tex]moles\times {\text {Molar mass}}=2.18\times 223.2g/mol=486.6[/tex]
percent yield =[tex]\frac{374.7g}{486.6g}\times 100=77.0\%[/tex]
Ram has power of 550 watt.What does it mean?
Answer:
for electricity, watts as in back to the future "1.21 jigga watts"!
Explanation:
TRUE OR FALSE? Alloys are used more than pure metals because they are generally softer and less likely to react with air or water. WILL GIVE BRAINLIEST
Answer:
False
Explanation:
They’re used cause they’re generally harder than pure metals
Alloys are used much more than pure metals because they are generally stronger and less likely to react with air or water...
So I would say false
What is the specific rotation of a sample of carvone that is an equal mixture of the R and S enantiomers
Answer:
Zero
Explanation:
An an equal mixture of the R and S enantiomers of carvone is called a racemic mixture.
In a racemic mixture, the R enantiomer rotates plane polarized light in one direction while the S enantiomer rotates plane polarized light in another direction.
This cancels out the rotation due to each enantiomer since they are equal in magnitude but opposite in direction leading to a specific rotation of zero for the racemic mixture.
Why is it necessary to add concentrated HCl, then water, rather than a solution of HCl to the eudiometer tube
If we add water to a concentrated acid, then the solution may boil very violently, splashing concentrated acid. If add acid to water, the solution that forms is very dilute and a small amount of heat is released.
Why do we add acid to water?When a strong acid is poured into water, it flows down the flask and mixes much better, so no boiling takes place. The addition of water to acid forms an extremely concentrated solution of acid initially. A large amount of heat is released and the solution may boil very violently, splashing concentrated acid out of the beaker and all this because the reaction is exothermic in nature.
The reason this takes place is due to a large amount of energy liberated in the hydration reaction of concentrated ions. Therefore, we add acid to water dropwise for the dilution with constant stirring and not water to acid directly.
If we add water to acid, then an exothermic reaction occurs and the solution may boil very violently. To form the dilute solution of any strong acid, you should add acid to water and the small amount of heat released is not sufficient to vaporize and spatter it.
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Question 2 of 25
Rain exists in which phase?
O A Liquid
O B. Solid
C. Plasma
D. Gas
Answer:
liquid
Explanation:
correct answer hope it helps
What evidence should Mitchell collect to BEST support the second law of thermodynamics?
Answer:
The Second Law of Thermodynamics poses an insurmountable problem for ... More time will make things worse for the Darwinist, not better. ... error fail-safe and proof-reading devices utilized for quality control, assembly ... No one really supports the idea that the sun + non life = life
Explanation:
According to the second law of thermodynamics, the energy of the universe is conserved but the entropy of the universe is continuously increasing.
What is the second law of thermodynamics?The second law of thermodynamics put some restrictions on the direction of heat transfer and attainable efficiencies of heat engines. This law stated that any spontaneously happening process will lead to an escalation in the entropy (S) of the universe.
This law explains that the entropy of an isolated system will never decrease with time. Mathematically, the 2nd law of thermodynamics:
ΔS (universe) > 0
where ΔS of the universe is the change in the entropy of the universe.
The second law of thermodynamics provides the criterion for the feasibility of any physical or chemical process. A physical or chemical process cannot take place unless it must follow both the 1st and 2nd laws of thermodynamics.
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On average what is the time between collisions of a xenon atom at 300 K and (a) one torr pressure; (b) one bar pressure.
Answer:
(a). 132 × 10^-9 s = 132 nanoseconds.
(b)..176.5 pico-seconds.
Explanation:
(a). At one torr, the first thing to do is to find the speed and that can be done by using the formula below;
Speed = [ (8 × R × T)/ Mm × π]^1/2.
Where Mm = molar mass, T = temperature and R = gas constant.
Speed= [ ( 8 × 8.314 × 300)/ 131.293 × π × 10^-3)^1/2. = 220m/s.
The next thing to do now is to calculate for the degree of collision which can be calculated by using the formula below;
Degree of collision = √2 × π × speed × d^2 × pressure/ K × T.
Note that pressure = 1 torr = 133.32 N/m^2 and d = collision diameter.
Degree of collision = √2 × π × 220 × (4.9 × 10^-10)^2 × 133.32/ 1.38 × 10^-23 × 300.
Degree of collision = 7.55 × 10^6 s^-1.
Thus, 1/ 7.55 × 10^6. = 132 × 10^-9 s = 132 nanoseconds.
(b). At one bar;
1/10^5 × 10^3 × 56.65 = 1.765 × 10^-10 = 176.5 pico-seconds.
Question 1 of 7
Which sentence correctly explains the change that occurs when ice melts?
Ice melting is a physical change, and the state of the substance remains the same.
Ice melting is a physical change, and the mass of the substance remains the same.
оо оо
Ice melting is a chemical change, and the state of the substance remains the same.
Ice melting is a chemical change, and the mass of the substance remains the same.
Answer:
Explanation:B ice melting is a phiyscal change and the mass of the substance remains the same
Answer:
b
Explanation:
The three lines in this Lewis dot structure represent the.
A)
three valence electrons of dinitrous oxide.
B)
six electrons in the triple bond of diatomic nitrogen.
C)
three electrons joining two nitrogen atoms in a diatomic molecule.
D)
three double bonds between the valence electrons of diatomic nitrogen.
Answer:
B) . six electrons in the triple bond of diatomic nitrogen
Explanation:
The three line in this Lewis dot structure represents the six electrons in the triple bond of diatomic nitrogen.
Nitrogen is made up of 7 electrons with 5 valence ones.
A lewis structure is made up of the symbol of the element surrounded by dot to represent the valence electrons.
In this nitrogen molecule, both species share 6 electrons. This makes each nitrogen atom isoelectronic with neon.
in the following chemical reaction between H_2 and Cl_2 to produce HCl, what is the sum of the mass of HCl produced plus the mass of left over reactants when 0.40 g of H_2 completely reacts with 12.35 g of Cl_2?
H_2(g) + Cl_2(g) → 2HCl(g)
Answer:
Left over mass of hydrogen = 0.06 g
Mass of HCl produced = 12.41 g
Explanation:
Given data:
Mass of H₂ = 0.40 g
Mass of Cl₂ = 12.35 g
Mass of left over reactant = ?
Mass of HCl produced = ?
Solution:
Chemical equation:
H₂ + Cl₂ → 2HCl
Number of moles of H₂:
Number of moles = mass / molar mass
Number of moles = 0.40 g/ 2 g/mol
Number of moles = 0.2 mol
Number of moles of Cl₂:
Number of moles = mass / molar mass
Number of moles = 12.35 g/ 71 g/mol
Number of moles = 0.17 mol
Now we will compare the moles of HCl with H₂ and Cl₂.
H₂ : HCl
1 : 2
0.2 : 2×0.2 = 0.4
Cl₂ : HCl
1 : 2
0.17 : 2 × 0.17 = 0.34
Chlorine is limiting reactant.
Mass of HCl produced:
Mass = number of moles × molar mass
Mass = 0.34 mol × 36.5 g/mol
Mass = 12.41 g
Leftover mass of hydrogen:
Cl₂ : H₂
1 : 1
0.17 : 0.17
Number of moles of H₂ react with Cl₂ are 0.17.
Moles remain unreacted = 0.2 - 0.17 = 0.03 mol
Mass left over:
Mass = number of moles × molar mass
Mass = 0.03 mol × 2 g/mol
Mass = 0.06 g
The sum of the mass of HCl produced plus the mass of left over reactants is:
Mass of hydrogen = 0.06 g
Mass of HCl = 12.41 g
Chemical ReactionGiven:
Mass of H₂ = 0.40 g
Mass of Cl₂ = 12.35 g
Mass of left over reactant = ?
Mass of HCl produced = ?
Chemical equation: H₂ + Cl₂ → 2HClNumber of moles of H₂:
Number of moles = mass / molar mass
Number of moles = 0.40 g/ 2 g/mol
Number of moles = 0.2 mol
Number of moles of Cl₂:
Number of moles = mass / molar mass
Number of moles = 12.35 g/ 71 g/mol
Number of moles = 0.17 mol
The moles of HCl with H₂ and Cl₂.
H₂ : HCl
1 : 2
0.2 : 2×0.2 = 0.4
Cl₂ : HCl
1 : 2
0.17 : 2 × 0.17 = 0.34
The chlorine is limiting reactant.
Mass of HCl produced:
Mass = number of moles × molar mass
Mass = 0.34 mol × 36.5 g/mol
Mass = 12.41 g
Leftover mass of hydrogen:
Cl₂ : H₂
1 : 1
0.17 : 0.17
Number of moles of H₂ react with Cl₂ are 0.17.
Moles remain unreacted = 0.2 - 0.17 = 0.03 mol
Mass left over:
Mass = number of moles × molar massMass = 0.03 mol × 2 g/molMass = 0.06 gLearn more about "Moles":
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4. Question: What effect does the amount of light have on plant growth?