Answer:
5.452 cal/g
Explanation:
45.8 cal / 8.4 g = 5.4523 cal/g
384.72 J is the heat of fusion of the substance.
What is the heat of fusion?It is the change in the value of the enthalpy by providing energy i.e. heat, for a specific quantity of the substance.
Given data:
Heat of fusion =?
Mass of substance = 8.4 g
Unknown:
Amount of energy required to melt the given mass = 45.8 cal
Solution:
To solve this problem, the amount of energy required to melt the substance is given as;
H = m L
m is the mass
L is the heat of fusion
Insert the given parameters and solve;
H = 8.4 g x 45.8 cal = 384.72 J
Hence, 384.72 J is the heat of fusion of the substance.
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Which statement describes an electron?
O It has a positive charge and is located in the nucleus.
OIt has a positive charge and is located in orbitals around the nucleus.
O It has a negative charge and is located in the nucleus.
O
It has a negative charge and is located in orbitals around the nucleus.
Answer:
D.) It has a negative charge and is located in orbitals around the nucleus.
Explanation:
Electrons always have a negative charge. Since electrons can be shared or donated/received, they must be located in the orbitals around the nucleus. Protons, which have a positive charge, and neutrons, which are neutral, are located in the nucleus.
what makes PLA hydrophilic?
Hydrogen peroxide is a liquid that decomposes to form oxygen gas and
water. The occasional bubble you might see in a beaker that contains
hydrogen peroxide is evidence of this reaction. But if a small amount of
manganese oxide powder is added to the beaker, many small bubbles start
forming in the liquid. What part does the manganese oxide play in this
reaction?
A. It is a catalyst that increases the rate of the reaction.
B. It is a substance that supplies extra energy for the reaction.
C. Its addition to the liquid makes molecules of hydrogen peroxide
move faster.
D. It is a reactant that is necessary for the reaction to begin.
SUBMIT
What is an open system?
A. A system that allows energy to move in and out but not mass
B. A system that allows energy and mass to move in and out of it
C. A system that allows mass to move in and out but not energy
OD. A system that does not allow energy or mass to move in or out of
it
Answer:
Open system :-
B. A system that allows energy and mass to move in and out of it.
Hope it helps!
7.71 Classify each of the following as exothermic or endothermic:
a. CHÂ(g) + 2O₂(g) —^> CO₂(g) + 2H₂O(g) + 802 kJ
b. Ca(OH)₂(s) + 65.3 kJ →→→ CaO(s) + H₂O(l)
c. 2Al(s) + Fe₂O3(s) — Al₂O3(s) + 2Fe(s) + 850 kJ
A. Heat is released, so the reaction is exothermic.
B. Heat is absorbed, so the reaction is endothermic.
C. Heat is released, so the reaction is exothermic.
A sample of 0.0084 mol of HCl is dissolved in water to make a 1500 mL solution. Calculate the molarity of the HCl solution, the [H3O+] and the pH. For a strong acid such as HCl, the [H3O+] is the same as the molarity of the HCl solution.
A solution prepared by dissolving 0.0084 moles of HCl in 1500 mL of solution has a Molarity of HCl of 5.6 × 10⁻³ M, a Molarity of H₃O⁺ of 5.6 × 10⁻³ M and a pH of 2.3.
What is Molarity ?Molarity (M) is the amount of a substance in a certain volume of solution. Molarity is defined as the moles of a solute per liters of a solution. Molarity is also known as the molar concentration of a solutionA solution is prepared by dissolving 0.0084 moles of HCl in 1500 mL of solution. The molarity of HCl is:
[HCl] = 0.0084 moles / 1.5 L
= 5.6 × 10⁻³ M
HCl is a strong acid according to the following equation.
HCl(aq) + H₂O(l) ⇒ Cl⁻(aq) + H₃O⁺(aq)
Thus, the concentration of H₃O⁺ will be equal to the initial concentration of HCl, 5.6 × 10⁻³ M.
Now, we will calculate the pH of the solution using its Formula ;
pH = - log[H₃O⁺]
= - log [5.6 × 10⁻³]
= 2.3
Hence, A solution prepared by dissolving 0.0084 moles of HCl in 1500 mL of solution has a Molarity of HCl of 5.6 × 10⁻³ M, a Molarity of H₃O⁺ of 5.6 × 10⁻³ M and a pH of 2.3.
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What can help engineers develop ways to prevent rusting?
OA. Understanding the solubility of metal ions
B. Understanding double-displacement reactions
C. Understanding oxidation-reduction reactions
D. Understanding the phase changes of metals
Answer: Understanding oxidation-reduction reactions
Explanation:
Rusting occurs when electrons are exchanged between iron and oxygen.
Classify each of the following substances as a compound or element.
a. Gold _____________
b. Ethanol _____________
c. Sugar _____________
d. Sulfur _____________
e. Hydrogen gas______
f. Carbon dioxide_______
Answer:
A. Element
B. Compound
C. Compound
D. Element
E. Compound
F. Compound
Explanation:
Elements are what is already on the periodic table and compounds are the substances created when they are combined.
The chemist discovers a more efficient catalyst that can produce ethyl butyrate with a 78.0 % yield. How many grams would be produced from 7.45 g of butanoic acid and excess ethanol?
Express your answer in grams to three significant figures.
7.66g of ethyl butyrate is produced.
The reaction is
CH₃CH₂CH₂COOH + CH₃CH₂OH ----> CH₃CH₂CH₂COOCH₂CH₃
The molar mass of butanoic acid is 88.11g/molWe have 7.45g of butanoic acidThe moles of butanoic acid we have is 7.45/88.11 = 0.0845 molIf the yield is 100%, 1 mole of butanoic acid gives 1 mole of ethyl butyrateBut the reaction yield is 78%1 mole of butanoic acid gives 0.78 mole of ethyl butyrateFrom 0.0845 mol of butanoic acid we get 0.78 x 0.0845 = 0.66 mol of ethyl butyrate.
The molar mass of ethyl butyrate is 116.16g/mol
So 0.66 x 116.16 = 7.66g
7.66g of ethyl butyrate is produced.
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If an element has 11 protons and 12 neutrons and 11 electrons, what is the atomic mass of the element?
The atomic mass of the unknown element is; 23
How to find the atomic mass of an element?We are given that;
Number of protons = 11
Number of Neutrons = 12
Number of Electrons = 11
Now, formula for atomic mass is;
Atomic mass = Number of Neutrons + Number of Electrons
Atomic Mass = 12 + 11
Atomic Mass = 23
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Question 4
2 pts
2 NH3 + 3 CuO g 3 Cu + N₂ + 3 H₂O
In the above equation how many moles of water can be made when 14 moles of NH3 are
consumed?
Answer:
9.33
Explanation:
balanced chemical equation:
2NH₃ + 3CuO → 3Cu + N₂ + 3H₂O
14 moles of NH3
2NH₃ → 3H₂O
14 * 2/3 = 9.33
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Na2 C6H6O7 (sodium hydrogen citrate)
Express the mass of sodium to three significant figures.
mNa =
The exact mass of one Na - atom is 22.98977 amu and thus, the weight of two sodium atoms in present in Na₂C₆H₆O₇ is 45.979539 g/mol.
What is Molar mass ?The molar mass of a substance is the mass in grams of 1 mole of the substance.
We can obtain a substance's molar mass by summing the molar masses of its component atoms.
Mass of one Na atom = 22.98977
Mass of two Na atom = 22.98977 x 2
= 45.97954
= 45.9 (up to 3 Significant figures)
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? If a weaker solution of sodium bicarbonate was used in beaker b, would that solution require more or less hydrochloric to neutralize it and why?
Answer:
less HCL acid is required to neutralize a weaker solution of base (sodium bicarbonate).
Explanation:
How many grams S03
are needed to make 400g
H₂So4 in 49%
160 g of SO3 are needed to make 400 g of 49% H2SO4.
How many grams of SO3 are required to prepare 400 g of 49% H2SO4?The equation of the reaction for the formation of H2SO4 from SO3 is given below as follows:
[tex]SO_{3} + H_{2}O \rightarrow H_{2}SO_{4}[/tex]
1 mole of SO3 produces 1 mole of H2SO4
Molar mass of SO3 = 80 g/mol
Molar mass of H2SO4 = 98 g/mol
80 g of SO3 are required to produce 98 og 100%H2SO4
mass of SO3 required to produce 400 g of 100 %H2SO4 = 80/98 × 400 = 326.5 g of SO3
Mass of SO3 required to produce 49% of 400 g H2SO4 = 326.5 × 49% = 160 g
Therefore, 160 g of SO3 are needed to make 400 g of 49% H2SO4.
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A hot-air balloon has a pressure of 0.715 atm while the temperature outside is 200C. What will the pressure be if the temperature drops to 5C while the volume remains constant?
1.12 kPa
11.2 atm
1203 atm
1.12 atm
The ideal gas law (PV = nRT) relates the macroscopic properties of ideal gases. An ideal gas is a gas in which the particles (a) do not attract or repel one another and (b) take up no space (have no volume).
From the question given above, the following data were obtained :
Initial pressure (P₁) = 0.715 atmInitial temperature (T₁) = 200 °CFinal temperature (T₂) = 195 °CVolume = constantFinal pressure (P₂) = ?Now, Let's convert celsius temperature to Kelvin temperature ;
T(K) = T(°C) + 273
Initial temperature (T₁) = 200 °C = 200 °C + 273 = 473 KFinal temperature (T₂) = 195 °C = 195 °C + 273 = 462 KNow, we shall can determine the final pressure (P₂) ;
Initial pressure (P₁) = 0.715 atmInitial temperature (T₁) = 473 KFinal temperature (T₂) = 462 KFinal pressure (P₂) = ?P₁ / T₁ = P₂ / T₂
0.715 / 473 = P₂ / 462
473 × P₂ = 0.715 × 462
P₂ = 0.69 atm
Thus, the final pressure of the hot air balloon is 0.69 atm
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ements
tton
2 NH3 + 3 CuO -->3 Cu + N₂ + 3H₂O
In the above equation how many moles of N₂ can be made when 156.1 grams of CuO are
consumed?
Round your answer to the nearest tenth. If you answer is a whole number like 4, report
the answer as 4.0
Use the following molar masses. If you do not use these masses, the computer will mark
your answer incorrect.:
Element Molar Mass
Hydrogen 1
Nitrogen 14
Copper 63.5
Oxygen 16
Answer: The amount of moles that can be produced when 156.1 grams of CuO are consumed is .653 moles.
Explanation: The first thing to do is to convert the 156.1 grams of Copper(II) Oxide (CuO).
In order to convert the 156.1 grams of Copper(II) Oxide to moles we have to first calculate the molar mass of Copper(II) Oxide. This can be done by simply adding the Copper's molar mass, 63.5, to the Oxygen's molar mass, 16.
16 g + 63.5 g = 79.5 g
Once you have obtained the molar mass of the Copper (II) Oxide you can then proceed to convert the 156.1 grams from before into moles.
This is done by multiplying 156.1 grams by 1 mole / 79.5 grams.
[tex]156.1 g *1 moles/79.5 g = 1.96 moles[/tex]
Now that you have calculated the 1.96 moles of Copper(II) Oxide, you need to set up an equation to convert between moles amounts.
This can be done by looking at the coefficients in the chemical equation. So, in this chemical reaction, it tells us for every 3 moles of CuO there is 1 moles of N2.
With this we can write a conversion equation as follows.
[tex]1.96*\frac{1}{3} = .653[/tex]
*Note: in conversion equations the denominator should match the units and or element being multiplied by the other fraction in the numerator. Such as in this instance the 1.96 moles of CuO and 3 moles of CuO are the same.
So, the amount of moles of N2 that can be made when 156.1 grams of CuO are consumed is .653 moles.
Answer:
0.7 mole N₂
Explanation:
To find the amount of N₂ produced, you need to (1) convert grams CuO to moles CuO (via the molar mass) and then (2) convert moles CuO to moles N₂ (via mole-to-mole ratio from reaction coefficients).
The molar mass is the sum of the element molar masses times their quantities. The ratios/conversions should be arranged in a way that allows for the cancellation of units (desired unit in the numerator).
Molar Mass (CuO): 63.5 g/mol + 16 g/mol
Molar Mass (CuO): 79.5 g/mol
2 NH₃ + 3 CuO ----> 3 Cu + 1 N₂ + 3 H₂O
^ ^
156.1 g CuO 1 mole 1 mole N₂
------------------- x ----------------- x ---------------------- = 0.7 mole N₂
79.5 g 3 moles CuO
0.160g of Mg is equal to how many moles Mg
The 0.160 grams of Mg is equal to 0.00658 moles of Magnesium (Mg).
Given,
Mass of Mg, m=0.160g
The atomic mass of Mg is 24.31 g.
The number of moles can be represented as the ratio of the given mass of the atom/molecule to the Atomic/Molar mass of the atom/molecule.
Atomic mass can be defined as the mass of the one mole of an atom and Similarily, molecular mass can be defined as the mass of one mole of a molecule.
Number of moles, n=Given mass/Molar mass
n=0.160g/(24.31g/mol)=0.00658 moles
Hence, the 0.160 grams of Magnesium (Mg) is equal to 0.00658 moles of Magnesium (Mg).
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6.67 x 10-3 g of arsenic (As) is found in a 0.600 L sample of water. If the density of this
sample is 1.00 g/mL, what is the concentration of arsenic in ppm?
ppm = mg/L = mg/kg
6.67 x 10⁻³ g = 6.67 mg
ppm = 6.67 mg : 0.6 L = 11.12
PLEASE HELP ASAP!!!!!!!!!!!!!!!
Answer:
A and B
Explanation:
A is crust
B is mantle
3A. The following skeletal oxidation-reduction reaction occurs under basic conditions. Write the balanced REDUCTION half reaction.
Cl- + SiO32- Cl2 + Si
Reactants Products
3B.
The following skeletal oxidation-reduction reaction occurs under basic conditions. Write the balanced OXIDATION half reaction.
Bi + HPO32-Bi(OH)3 + H2PO2-
Reactants Products
4A. The following skeletal oxidation-reduction reaction occurs under acidic conditions. Write the balanced REDUCTION half reaction.
Cd + SO42- Cd2+ + H2SO3
Reactants Products
4B. The following skeletal oxidation-reduction reaction occurs under acidic conditions. Write the balanced OXIDATION half reaction.
Mn2+ + NiO2MnO4- + Ni2+
Reactants Products
The balanced redox equations of the reactions are:
[tex]SiO_{3}^{2-} + 3\:H_{2}O + 4\:e^{-} \rightarrow Si + 6\:OH^{-}[/tex][tex]2\:Bi + 6\:OH^{-} \rightarrow 2\:Bi(OH)_{3} + 6\:e^{-}[/tex] [tex]SO_{4}^{2-} + 4\:H^{+} + 2\:e^{-} \rightarrow H_{2}SO_{3} + H_{2}O[/tex][tex]Mn^{2+} + 4\:H_{2}O \rightarrow MnO_{4}^{-} +8\:H^{+} + 5\:e^{-}[/tex]What are balanced redox equations?Balanced redox equations are those in which the atoms and electrons transferred are equal on both sides of the equation.
The balanced redox equations of the reactions are given below:
(3a) Balanced REDUCTION half reaction of the equation under basic conditions:
[tex]SiO_{3}^{2-} + 3\:H_{2}O + 4\:e^{-} \rightarrow Si + 6\:OH^{-}[/tex](3b)Balanced OXIDATION half reaction of the equation under basic conditions:
[tex]2\:Bi + 6\:OH^{-} \rightarrow 2\:Bi(OH)_{3} + 6\:e^{-}[/tex](4a) Balanced REDUCTION half reaction of the equation under acidic conditions:
[tex]SO_{4}^{2-} + 4\:H^{+} + 2\:e^{-} \rightarrow H_{2}SO_{3} + H_{2}O[/tex](4b) Balanced OXIDATION half reaction of the equation under acidic conditions:
[tex]Mn^{2+} + 4\:H_{2}O \rightarrow MnO_{4}^{-} +8\:H^{+} + 5\:e^{-}[/tex]Therefore, the balanced oxidation and reduction half reactions are balanced by adding the numerical coefficients to the reacting species as well hydrogen ions, hydroxide ions, water molecules and electrons to the appropriate side of the reactions.
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PLEASE HELP ASASP!!!!!!!
Answer:
B
Explanation:
I took the test
Which of the following statements would correct one of the roles listed in the table?
O Glucose combines with water to form carbon dioxide,
OGlucose reacts with carbon dioxide during photosynthesis.
OOxygen is formed along with glucose during photosynthesis.
O Chlorophyll stores chemical energy needed for photosynthesis.
Answer:
a
Explanation:
glucose combined with water to form carbon dioxide
Answer:
Option C
Explanation:
Because during photosynthesis the reaction is as per following
CO_2+H_2O—»C_2H_12O_6+O_2Clearly
Glucose nd oxygen are formed
1. Write the reaction rate expressions for the following reactions in terms of the disappearance of the reactants and the appearance of products: 1-(aq)+ OCI-(aq)-CI-(aq)+OI-(aq)
In terms of the disappearance of the reactants, the rate equations are R= -kd[I-]/dt and -kd[OCl-]/dt.
What is an ionic reaction?The term ionic reaction refers to the reaction that takes place between two ions. In this case, the ionic reaction is; I-(aq) + OCl-(aq) -------> Cl-(aq) + OI-(aq).
The rate equations in terms of the disappearance of the reactants is;
R= -kd[I-]/dt
And
R = -kd[OCl-]/dt
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7. Name the representative particle (atom, molecule, ion or formula unit) of Radon
Answer: A representative particle can be an atom, and an ion. a molecule, or a formula unit.
Explanation:
A representative particle is the smallest unit in which a substance naturally exists. For the majority of elements, the representative particle is the atom. Iron, carbon, and helium consist of iron atoms, carbon atoms, and helium atom, respectively.
Radon is a naturally occurring radioactive gas that is odorless and tasteless.
Atoms-the smallest particle of an element
Ions-atoms with positive or negative charges.
Molecules- two or more covalently bonded atoms.
Formula units- the simplest ratio of ions that make up an ionic compound.
pls tell this answers
Answer:
okay
Explanation:
9 . acidic
10. hydrogen
answer the following questions
11. Gold as a precious metal is used widely in making jewelry items. This metal is preferred over others for jewelry pieces for various reasons. One important reason for its popularity is that it does not react with atmospheric moisture and therefore, it does not rust.
12. corrosion is defined as rust it's due to humidity and moisture
13. Sulphur appears much below chlorine in the reactivity table and cannot displace chlorine from dilute HCl.
14. Highly conductive metal
Surpassed only by silver, copper is a highly conductive metal. This means electricity can pass through it with greater ease, making it ideal for use in electrical wires. Companies can use other conductive metals to create electrical wires.
15. Corrosion
Copper metal when exposed to air turns green in color due to corrosion. When the copper vessel is exposed to air in the rainy season, the metal reacts with gases, moisture, and atmospheric gases to form a mixture of copper carbonate and copper hydroxide. This gives a green color to the surface of the copper meta
16. Silicon
silicon is the backbone of the electronics industry. Because silicon is the reason for the fast development happened in the field of electronics. therefore, silicon is the backbone of electronics.
17. High chemical reactivity
Sodium is stored under kerosene because of its high chemical reactivity with almost all of the other elements (for example oxygen from the air which oxidizes it instantly). Kerosene and mineral oil are the only chemicals that make sodium inert. Usually, when Na reacts with a solvent it liberates hydrogen gas from its composition.
18. Metal oxides are oxides of metals. Nonmetal oxides are oxides of nonmetals. The main difference between metal oxides and nonmetal oxides is that metal oxides are basic compounds whereas nonmetal oxides are acidic compounds.
19. Silver is more likely to tarnish near a petroleum refinery than in a place far away from it because when silver reacts with petroleum or hydrogen sulfide present in it as a pollutant in the air, it starts forming a black coating of silver sulfide.
20. A noble metal is ordinarily regarded as a metallic chemical element that is generally resistant to corrosion and is usually found in nature in its raw form. Gold, platinum, and the other platinum group metals (ruthenium, rhodium, palladium, osmium, iridium) are most often so classified. Silver, copper, and mercury are less often to sometimes included as noble metals although each of these usually occurs in nature combined with sulfur.
which of the following best describes what happens during nuclear fusion
Answer:
Nuclear fusion is a kind of nuclear reaction in which two lighter nuclei combine under suitable conditions to form heavier nuclei under suitable conditions. A lot of energy is released in this process.
A team of scientists altered the DNA of E. coli bacteria. The bacteria thus developed had the ability to generate insulin exactly identical to the human insulin molecule. What could be the likely impact of this biotechnology on the individual and the society?
The medical costs for insulin-dependent patients would rise.
Large-scale insulin could be produced in relatively lesser time.
The price of insulin available from sources other than bacteria may fall.
The patients who take insulin may become infected with E. coli bacteria.
Answer:
Large-scale insulin could be produced in relatively lesser time.
Explanation:
We already sort of do this where we infect the bacteria with a plasmid containing our insulin gene and it causes them to produce insulin. Since the question is saying that we edited their DNA directly, now these bacteria don't need to be infected with plasmid b/c now they can just pass these genes onto their offspring.
This will allow us to make TONS of insulin cuz bacteria are crazy good at making stuff and growing.
A camel's hump is a trait that evolved through the process of ____________ to allow the camels to survive for longer periods without water.
A.
natural selection
B.
fossilization
C.
mutualism
D.
genetics
Answer:
Natural Selection
The answer is:
A. Natural Selection
Approximately 50% of our bone is chemically calcium phosphate, Ca3(PO4)2
If an adult has 12 kg of bone, calculate the mass of calcium is present
Calculate the pH of a solution that is 0.113 M HCI.
Simplified concentration
[tex]\\ \rm\Rrightarrow 1.13\times 10^{-2}M[/tex]
Now
[tex]\\ \rm\Rrightarrow pH=-log[H^+][/tex]
[tex]\\ \rm\Rrightarrow pH=-log(1.13\times 10^{-2})[/tex]
[tex]\\ \rm\Rrightarrow pH=-log1.13-log10^{-2}[/tex]
[tex]\\ \rm\Rrightarrow pH=-0.05+2[/tex]
[tex]\\ \rm\Rrightarrow pH=1.95[/tex]
Highly acidic