Answer:
1) 5 kJ
2) 125 moles
3) 81.33 kJ
4) 135.9 grams
5) 15.165 kJ
6) 97.6 J
Explanation:
1) Molar mass of ice (water) = 18.015 g/mol
Number of moles, n, of ice = mass/(molar mass) = 15/18.015 = 0.833 moles
ΔHfus = 6.00 kJ/mol
Energy required, E = ΔHfus × n = 0.833 × 6 = 4.996 ≈ 5 kJ
2) Number of moles of ice that can be melted by E = 750 kJ is given by the equation;
n = E/(ΔHfus) = 750/6 = 125 moles
3) Given that ΔHvap = 40.7 kJ/mol, we have;
Number of moles of water, n = 36/18.015 = 1.998 ≈ 2 moles
Heat required = ΔHvap × n = 40.7 × 2 = 81.33kJ
4) Given that heat removed, ΔH= 307 kJ, we have;
n = ΔH/ΔHvap = 307/40.7 = 7.543 moles
Mass of water = Number of moles × Molar mass = 7.543 × 18.015 = 135.9 grams
5) Energy required, E for iodine to melt = Number of moles of iodine × ΔHfus of iodine
Number of moles of iodine = Mass of iodine/(Molar mass of iodine)
Number of moles of iodine = 248/126.9 = 1.954 moles
Energy required, E for iodine to melt = 1.954 × 7.76 = 15.165 kJ
6) Energy required, E for 4.24 g of lead to melt = Number of moles of lead × ΔHfus of lead
Number of moles of lead= Mass of lead/(Molar mass of lead)
Number of moles of iodine = 4.24/207.2 = 0.0205 moles
Energy required, E for iodine to melt = 0.0205 × 4.77 = 9.76 × 10⁻² kJ = 97.6 J.
Name at least 6 methods of seperation
Answer:
HandpickingThreshingWinnowingSievingEvaporationDistillationFiltration or SedimentationSeparating FunnelMagnetic SeparationExplanation:
You said at least 6 methods meaning I can give more than 6.
Hope it helps.
Explanation:
Filtration
evaporation
decantation
chromatography
fractional distillation
sublimation
lens coating are made of A.teflon B.bakelite C.melamine D.PVC
Answer:
C. melamine
Explanation:
a thin coating that eliminates reflections and glare from the front and back surfaces of your lenses.
which of the following us not a property of salt in the ionic and covalent properties lab
Explanation:
I think Low melting point
because NaCl (salt has mp 801 degC)
Water has mp 0 degC
While hiking in the mountains, a scientist sees a unique flower. What is the
best way for the scientist to share this observation with another scientist for
the purpose of identifying the plant?
O
A. The scientist can memorize the flower's appearance.
B. The scientist can take and email a photograph of the flower.
C. The scientist can cut off a tiny piece of the flower to examine
using a microscope.
O
D. The scientist can use a tape measure to make precise
measurements of the flower.
Answer:
B or C seem most appropriate
Explanation:
Memorising the apperaranve of a unique flower, is not the best easy to prove something, because you could have just seen the description in a book, and it is least likely you will be believed.
Its B for apex users 100% correct
balancing chemical equation helpp me H3PO4+KOH---> K3PO4+H2O some one balance this please help me
Answer:
H3PO4 + 3KOH -> K3PO4 + 3H20
Answer:
hope its helpful to uh....
Balance the chemical equations
Answer:
Explanation:
1). Ca(NO₃)₂ + KI → CaI + K(NO₃)₂
This equation is incorrect.
When Ca⁺⁺ reacts with I⁻, final product is CaI₂
And when K⁺ react with NO₃⁻, final product is KNO₃
Hence the equation will be,
Ca(NO₃)₂ + KI → CaI₂ + KNO₃
Now we have to balance this equation.
Ca(NO₃)₂ + 2KI → CaI₂ + KNO₃
↓
Ca(NO₃)₂ + 2KI → CaI₂ + 2KNO₃
2). Ca(NO₃)₂ + KOH → CaOH + K(NO₃)₂
This equation is incorrect,
Since the reaction of Ca⁺⁺ with OH⁻ gives the final product Ca(OH)₂
And final product of K⁺ and NO₃⁻ is KNO₃
Therefore, the equation will be,
Ca(NO₃)₂ + KOH → Ca(OH)₂ + KNO₃
Now we will balance this equation by changing the coefficients of the molecules until the number of atoms on both the sides become equal.
Ca(NO₃)₂ + KOH → Ca(OH)₂ + 2KNO₃
↓
Ca(NO₃)₂ + 2KOH → Ca(OH)₂ + 2KNO₃
3). Ca(NO₃)₂ + Na₂C₂O₄ → CaC₂O₄ + 2Na(NO₃)₂
This equation is incorrect,
Since the reaction of Na⁺ and NO₃⁻ gives the final product NaNO₃.
Therefore, the correct equation will be,
Ca(NO₃)₂ + Na₂C₂O₄ → CaC₂O₄ + 2NaNO₃
This equation is in the balanced form.
A 0.200 g sample of unknown metal x is dropped into hydrochloride acid and realeases 80.3 mL of hydrogen gas at STP using ideal Gas law the number of miles of the unknown is
Answer:
The number of mole of the unknown metal is 3.58×10¯³ mole
Explanation:
We'll begin by calculating the number of mole hydrogen gas, H2 that will occupy 80.3 mL at stp.
This is illustrated below:
Recall:
1 mole of any occupy 22.4L or 22400 mL at stp.
1 mole of H2 occupies 22400 mL at stp.
Therefore, Xmol of H2 will occupy 80.3 mL at stp i.e
Xmol of H2 = 80.3/22400
Xmol of H2 = 3.58×10¯³ mole
Therefore, 3.58×10¯³ mole of Hydrogen gas was released.
Now, we can determine the mole of the unknown metal as follow:
The balanced equation for the reaction is given below:
X + 2HCl —> XCl2 + H2
From the balanced equation above,
1 mole of the unknown metal reacted to produce 1 mole of H2.
Therefore, 3.58×10¯³ mole of the unknown metal will also react to produce 3.58×10¯³ mole of H2.
Therefore, the number of mole of the unknown compound is 3.58×10¯³ mole.
How many moles of silver are equivalent to 2.408 x 10^24 atoms
The mole is used to measure small particles like atoms and molecules. The 4 moles of silver is equivalent to [tex]\bold{2.408 x 10^2^4 }[/tex] atoms.
Given here,
The number of atoms
[tex]\bold{2.408 x 10^2^4 }[/tex]
Number of moles = ?
1 mol of substance = [tex]\bold{ 6.02 x10^2^3}[/tex]
Hence,
moles of silver,
[tex]\bold {= \dfrac {2.408 x 10^2^4 } { 6.02 x10^2^3} }}\\\\\bold {= 4 mol}[/tex]
Therefore, the 4 moles of silver is equivalent to [tex]\bold{2.408 x 10^2^4 }[/tex] atoms.
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What Are Real Relationship Goals?
Answer:
Real relationship goals in chemistry is simple "emotion" that two people get when they share a special connection.
With carbon dioxide, what phase change takes place when pressure
increases from 1 atm to 10 atm at -40°C?
Carbon Dloxide Phase Diagram
Melting
point
Boling
point
20-
15-
Liquid
Pressure (atm)
10-
Solid
5-
Gas
0
0
00
-100
Temperature (°C)
A. A solid changes to a liquid.
B. A liquid changes to a solid.
O C. A liquid changes to a gas.
D. A gas changes to a liquid.
Answer:B. A liquid changes to a solid.
Explanation:
A Liquid changes to solid when pressure
increases from 1 atm to 10 atm at -40°C
What is the concept for this?The increase in pressure on liquid it forms a solidIf the pressure above the liquid is decreased sufficently, the liquid form a gas How to solve this problem?Here the Freezing point is -78.33°C i.e [-109°F]above this temperature CO2 remains in liquid stateSo, given at -40°C
CO2 will be in liquid state and as per the concept explained above by increasing the pressure on liquid we get the solid state
Thus , With CO2 a liquid phase change to a solid
phase when pressure increases 1 atm to 10atm at -40°C
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En la electrólisis del Cloruro de plomo se han depositado 2.6 gramos del metal en 20 minutos el peso atómico del plomo es 206 calculo la intensidad de la corriente eléctrica empleada AYUDENNNNN PLISSSS es para hoy!!!!!
Answer:
2.01 A
Explanation:
Para esta pregunta debemos empezar por la semi-reaccion del plomo:
[tex]Pb^+^2~_(_a_q_)~+~2e^-~->~Pb_(_s_)[/tex]
Se intercambian dos electrones en la semi-reacción del plomo. Si tenemos en cuenta la ecuación:
[tex]n=\frac{I*t}{z*F}[/tex]
Donde:
n= Moles depositados
I= Intensidad de corriente (en Amperios)
z= Numero de electrones intercambiados
F= Constante de faraday = 96484 C/mol
t=tiempo (en segundos)
Que conocemos de esta ecuación?
Los moles (se pueden calcular a partir de la masa atómica del plomo, 207.2 g/mol)
[tex]2.6~g~Pb\frac{1~mol~Pb}{207.2~g~Pb}=0.0125~mol~Pb[/tex]
El tiempo (hay que convertirlo a segundos):
[tex]20~min\frac{60~s}{1~min}=1200~s[/tex]
Z (Numero de electrones)
De acuerdo a la semi-reacción son intercambiados 2 electrones.
Por lo tanto podemos resolver para "I":
[tex]I=\frac{n*z*F}{t}=\frac{0.0125~mol*2*96484\frac{C}{mol}}{1200~s}[/tex]
[tex]I~=~2.01~\frac{C}{s}=2.01~A[/tex]
Espero que sea de ayuda!
please hurry! :( according to boyle's law, what would happen to the pressure of a gas if the temperature were doubled as the number of moles and volume are held constant?
Answer:
A.
The hotter the object the faster the molecules so if the temperature is doubled the molecules go two times faster making the pressure double. Since the molecules are two times faster the pressure will be two times more because it is two times harder to keep the gas in.
Hope this helps
Explanation:
1.825 gm HCl is dissolved in 250 ml solution. What is the pH of that solution? Please answer with the explanation.
The first step is calculating the number of HCl moles. The molar mass of HCl is AH+ACl which is 1+35,5=36,5 g/mole. The formula for the pH is -lg[H+] where [H+] is the molar concentration of protons in the solution. To find the molar concentration we need to divide the number of moles by the volume(L).
We get the number of moles by dividing the mass given in the problem to the molar mass of the compound.1.825/36.5=0.05 moles of HCl so 0.05 moles of
H+.Molarity=n/V=0.05/0.25=0.2moles/liter.The pH is -lg0.2=2.321.
3Pb(s) + 2H3PO4(l) →
Answer:
3Pb(s) + 2H3PO4(l) →H3PO4 + Pb3(PO4)2 H2
Explanation:
I hope I helped you :P
Which is one way that analyzing ice benefits scientists who study ancient climates? Scientists can analyze frozen volcanic dust to help predict eruptions. Scientists can drill deep into the ice to collect ice cores. Scientists can use pollen grains in ice to make inferences about the climate area. Scientists can study tree rings in ice to learn more about past climates.
Answer:
The correct option is;
Scientists can drill deep into the ice to collect ice cores which contain trapped atmospheric gases
Explanation:
The study of past climates also known as paleoclimatology, is accomplished by acquiring information from proxy data sources which are physical environment characteristics that are preserved through time to remake the conditions of past climate
Past physical environmental characteristics, from which information about ancient climate can be gained are stored in nature's climate variability records including, ice cores, rings in tree stems, fossil pollen, sediments found in the waters of the ocean
The proxy sources provide a means of understanding the conditions of ancient climate before advent of climate measurement.
Therefore, one way that analyzing ice benefits scientists who study ancient climates is that scientists can drill deep into the ice to collect ice cores which contain trapped atmospheric gases from past climates.
Answer: B: Scientists can study the layers of ice cores to gather information about past atmospheric composition.
Explanation: Got it right on a test!
For each of the compounds, find the length of the longest carbon chain in the box provided.
CH,
CH3 -CH2-CH2-CH2-CH-CH2-CH2 - CH2 - CH3
CH,CH,CH,
HC
CH-CH2-CH3
CH,CH.CHCCH,CH,CH,
1
CH2
H.C CH.CH
CH3
<
Answer:
In First compound the longest chain contains 7 C atoms.
In the Second compound the longest chain contains 9 C atoms.
In the Third compound the longest chin contains 7C atoms.
Explanation:
In first compound the longest chain contains 7 carbon atoms.In the second compound the longest chain contains 9 carbon atoms.In the third compound the longest chin contains 7 carbon atoms.
What is an atom?An atom is defined as the smallest unit of matter which forms an element. Every form of matter whether solid,liquid , gas consists of atoms . Each atom has a nucleus which is composed of protons and neutrons and shells in which the electrons revolve.
The protons are positively charged and neutrons are neutral and hence the nucleus is positively charged. The electrons which revolve around the nucleus are negatively charged and hence the atom as a whole is neutral and stable due to presence of oppositely charged particles.
Atoms of the same element are similar as they have number of sub- atomic particles which on combination do not alter the chemical properties of the substances.
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Which statement correctly describes a feature of the rock cycle?
PA
Rocks are preserved through the process.
Rocks change from one type to another.
Different rock groups are not related to one another.
Rocks change from one type to another in a specific order.
Answer:
It’s D
Explanation:
Answer:
D Rocks change from one type to another in a specific order.
Explanation:
3. What simple laboratory test could be used to distinguish:
(a) butane and but-2-ene
(b) cyclohexane and cyclohexene
(c) but-i-ene and but-2-ene
Answer:
b) cyclohexane and cyclohexen
Classify the statements below as Weather or Climate. HELP ME WITH THIS The wind is blowing from the south. The average temperature for February in Australia is 19 degrees Celsius. The average rainfall for June in Kenya is 3.3cm. 10mm of rain fell today. There is a thunderstorm warning. The average high temperatures for July in Yellowknife is 32.5 degrees Celcius. The wind is blowing at 56 km / hr. It is usually cold in Ottawa in January. There was a cold weather advisory on Jan 21 2020. Hurricanes are most likely to hit the Gulf of Mexico and the Carribean.
Answer:
Weather:
- The wind is blowing from the south.
- There is a thunderstorm warning.
- The average high temperatures for July in Yellowknife is 32.5 degrees Celcius.
- The wind is blowing at 56 km / hr.
Climate:
- The average temperature for February in Australia is 19 degrees Celsius.
- The average rainfall for June in Kenya is 3.3cm.
- 10mm of rain fell today.
- It is usually cold in Ottawa in January. -There was a cold weather advisory on Jan 21 2020.
-Hurricanes are most likely to hit the Gulf of Mexico and the Carribean.
Explanation:
Hope it helps.
do you always have to begin with two compounds in a neutralization reaction
Answer:
Yes.
Explanation:
Only an acidic compound and then a basic compound react(neutralization reaction) to give a salt.
Acid+Base=Salt+Water.
Hope this helps❤❤❤
Yes, we always have to begin with two compounds in a neutralization reaction.
What is a neutralization reaction?A neutralization reaction can be defined as a chemical reaction in which an acid and base quantitatively react together to form salt and water as products.
When an acid and a base react, the reaction is called a neutralization reaction. That's because the reaction produces neutral products. Water is always one product, and salt is also produced. Salt is a neutral ionic compound.
Yes, we always have to begin with two compounds in a neutralization reaction.
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how many moles of O2 react with .75 moles of c10h22
Answer:
2 moles
Explanation:
Tick the correct choice and give reason why you have selected the particular choice. [20] 1. A cup of hot tea is left in the same room as a bowl of ice-cream. What is likely to happen to both after some time, if both are placed on the dining table? A. The tea becomes as cold as ice cream B. The ice cream becomes warmer than the tea C. The tea cools to room temperature, the ice cream melts and warms to room temperature D. The tea becomes colder than before but not as cool as the air in the room
Answer:
C. The tea cools to room temperature, the ice cream melts and warms to room temperature.
Explanation:
The tea's temperature was higher than room temperature. The ice cream's temperature was lower than room temperature. After some time, both items will become room temperature, which results in cooling and melting.
If a substance undergoes electrolysis and a brown solid forms on one electrode and a gas on the other, from this we can conclude the original substance must have been: a. An element b. A compound c. A mixture
Answer:
b. a compound.
Explanation:
Electrolysis is described as a mechanism in which ionic compounds are decomposed into their elements by transmitting a direct electric current via the compound in a liquid state. At the cathode, the cations are reduced and anions at the anode are oxidized. There is an exchange between ions and atoms in the electrolysis process caused by the addition or removal between electrons from the external circuit. As per the question, the original substance is a compound because the electrolysis method is used to obtain pure elements from their respective compound.
Which statement describes both homogeneous mixtures and heterogeneous mixtures?
The given question is incomplete, the complete question is:
Which statement describes both homogeneous mixtures and heterogeneous mixtures?
A.
Their components can be distinguished visually.
B.
Their components are combined in a fixed ratio.
C.
Their components can be separated by physical processes.
D.
They always contain a liquid component.
E.
They are considered to be pure substances.
Answer:
The correct answer is option C, that is, their components can be separated by physical processes.
Explanation:
A combination of two or more substances in which no reaction or chemical combination takes place is termed as a mixture. On the other hand, the atoms of different elements that are combined chemically in a fixed ratio are termed as a compound.
The mixtures, that is, whether homogenous or heterogeneous exhibits the tendency to get differentiated physically, on the other hand, compounds do not possess such a tendency. Like one can separate the mixture of alcohol and water by the process of distillation, as both the components exhibit distinct boiling points, that is, can be separated based on their physical characteristics.
On the other hand, if one desires to distinguish oxygen and hydrogen from water, then there is a need to dissociate the bonds present between the molecules of hydrogen and oxygen, which is its chemical property, not physical characteristics.
1. Describe potential long-term and short-term effects of exposure to chemicals.
Answer:
The answer to the question is explained below
Explanation:
A chemical is any substance or an element that can occur naturally or can be created artificially. Chemicals are found in many places like the soil, water, air. They can be found solely as an element without being combined with other elements, and they can also be found as a mixture in compounds.
Exposure to chemicals can be made possible through direct contact with the eye, broken skin. It can also be possible through Inhalation of gases, also through the mouth.
Long-term effects occur when an individual has been exposed to harmful chemicals over a long period of time, with the effect often fatal. Long-term exposure to chemicals include:
1. The weakening of the immune system
2. can cause cancer. For example, Carcinogens that cause cancer in humans, are gotten from exposures to Carbon Tetrachloride, Chloroform.
3. It can cause brain damage
4. It can lead to reproductive disorders
5. It can lead to eye damage, skin problems, and respiratory problems
Short-term effects occur when an individual has been exposed to harmful chemicals accidentally, or within a short period of time. As such, depending on the type of chemical, the amount the individual is exposed to, the effect is usually less fatal and can be addressed. Short-term exposure to chemicals include:
1. Skin or eye irritation
2. Headache
3. Nausea
4. Cough
5. Dizziness
6. Physical injuries
copper is heated in air it reacts with oxygen of air to form a black compound copper oxide in chemical equation
Answer:
Yes
Explanation:
copper is heated in air it reacts with oxygen of air to form a black compound
Which title is most appropriate for this table? ANSWERS: Uses of Functional Groups Involving Oxygen Natural Sources of Functional Groups Involving Oxygen Uses of Functional Groups Involving Halides and Amines Natural Sources of Functional Groups Involving Halides and Amines
Answer:
Uses of Functional Groups Involving Oxygen
Explanation:
From the table given above, we obtained the following:
1. The functional group of each compound contains oxygen.
2. The table shows the uses of each compound.
From the observations made above, we can say that the most appropriate title for the table is:
Uses of Functional Groups Involving Oxygen.
Answer:
A.Explanation:
first guy is right give him brainliest
A student weighs out a 6.64 g sample of , transfers it to a 500. mL volumetric flask, adds enough water to dissolve it and then adds water to the 500. mL tick mark. What is the molarity of cobalt(II) fluoride in the resulting solution
Answer:
the molarity of cobalt(II) fluoride in the resulting solution is = 0.137 M
Explanation:
Given that :
a student dissolves 6.64 g of CoF₂ into 500 mL of water
volume of the solution(water) = 500 mL = 0.50 L
The standard molar mass of CoF₂ is 96.93 g/mol
number of moles of CoF₂ = mass of CoF₂/molar mass of CoF₂
number of moles of CoF₂ = 6.64 g/96.93 g/mol
number of moles of CoF₂ = 0.0685 mol
The molarity of any given substance is known to be as the number of moles of solute dissolved in one litre of solution.
Thus ;
Molarity of cobalt(II) fluoride CoF₂ in the resulting solution is = number of moles / Volume in (L)
Molarity of cobalt(II) fluoride CoF₂ = 0.0685 mol/ 0.50 L
= 0.137 M
Thus ; the molarity of cobalt(II) fluoride in the resulting solution is = 0.137 M
Identify the correct statement regarding the strength of chemical bonds.
Weak bonds require more surface area to form than strong bonds.
A weak bond forms from a smaller change in energy compared to a strong bond.
Strong bonds occur with high temperature and weak bonds with low temperature.
Weak bonds require more heat to form than strong bonds.
Answer:
B.
Explanation:
A weak bond forms from a smaller change in energy compared to a strong bond.
A flexible container at an initial volume of 6.13 L contains 6.51 mol of gas. More gas is then added to the container until it reaches a final volume of 18.3 L. Assuming the pressure and temperature of the gas remain constant, calculate the number of moles of gas added to the container.
Answer:
the final mole of the flexible container = 12.92 moles
Explanation:
Given that :
initial volume of a flexible container = 6.13 L
initial mole of a flexible container = 6.51 mol
final volume of a flexible container = 18.3 L
final mole of a flexible container = ???
Assuming the pressure and temperature of the gas remain constant, calculate the number of moles of gas added to the container.
Therefore,
[tex]n= \dfrac{V_2*n_1}{V_1}[/tex]
[tex]n= \dfrac{18.3*6.51}{6.13}[/tex]
n = 19.43
[tex]n=n_1+n_2[/tex]
19.43 = 6.51 + n₂
n₂ = 19.43 - 6.51
n₂ = 12.92 moles
Thus; the final mole of the flexible container = 12.92 moles