Answer:
Ice melts into liquid water- endothermic
A process with a calculated positive q - endothermic
Wood burns in a fireplace - exothermic
A process with a calculated negative q - exothermic
Acid and base are mixed, making test tube feel hot - exothermic
Solid dissolves into solution, making ice pack feel cold - endothermic
Explanation:
An endothermic process is one in which heat is absorbed from the surroundings. The absorption of heat means that heat is removed from the surroundings hence the surroundings feel cool. When heat is absorbed, q is positive.
An exothermic process is one in which heat is released to the surroundings. The evolution of heat means that heat is released into the surroundings hence the surroundings feel hot . When heat is evolved, q is negative.
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Please
what is the formula for fluoride?
Answer:Chemical formula F −
Molar mass 18.998403163 g·mol−1
Conjugate acid Hydrogen fluoride
Explanation:
6. What is the number of moles of KF in a 29 gram sample?
a. 59.0 mols
C. 2.0 mols
b. 470 mols
d. 1684.9 mols
15 The Following statement describes which body system? It also produces blood cells, and stores calcium. It regulates endocrine as well. This specific system uses all bones & joints in your body. A. The Lymphatic System B.The Muscular System C.The Reproductive System D.The Skeletal System
How much energy is needed to evaporate 100g of water
Answer: you would have to remove 80 calories from 1 g of pure water at the freezing point, 0˚ C, to convert it to 1 g of ice at 0˚ C. Explanation:However, 540 calories of energy are required to convert that 1 g of water at 100˚ C to 1 g of water vapor at 100˚ C. This is called the latent heat of vaporization. On the other hand, you would have to remove 80 calories from 1 g of pure water at the freezing point, 0˚ C, to convert it to 1 g of ice at 0˚ C.
Graphite, an allotrope of carbon, is converted into cubic diamond through a process that may take a billion years or longer. As illustrated above, scientists can make synthetic diamonds using a certain process in about one week. However, these synthetic diamonds have carbon atoms in a hexagonal lattice. Diamonds with a carbon atoms in a cubic lattice are not produced even though they are thermodynamically more stable than hexagonal diamond. Which of the following best justifies why the synthetic process produces hexagonal diamond and not the more thermodynamically stable cubic diamond?
a. The amount of energy required to create new bonds between carbon atoms in cubic diamond is much greater than the amount of energy required to create hexagonal diamond.
b. The amount of energy required to create new bonds between carbon atoms in cubic diamond is much smaller than the amount of energy required to create hexagonal diamond.
c. The activation energy needed to form cubic diamond is much less than the activation energy needed to form hexagonal diamond.
d. The activation energy needed to form cubic diamond is much greater than the activation energy needed to form hexagonal diamond.
Answer:
The activation energy needed to form cubic diamond is much greater than the activation energy needed to form hexagonal diamond.
Explanation:
The activation energy refers to the minimum energy that reacting species must possess before they can undergo a particular chemical reaction.
This implies that if species do not possess the activation energy, they hardly undergo a given reaction. The activation energy is the barrier between reactants and products.
Hence, a reaction that has a very high activation energy occurs slowly or may not even occur. The activation energy needed to form cubic diamond is much greater than the activation energy needed to form hexagonal diamond hence the synthetic process produces hexagonal diamond and not the more thermodynamically stable cubic diamond.
Calculate the concentration of H3O⁺ in a solution that contains 1.8 × 10-5 M OH⁻ at 25°C. Identify the solution as acidic, basic, or neutral. A. 5.5 × 10-10 M, acidic B. 9.2 × 10-1 M, acidic C. 5.5 × 10-10 M, basic D. 1.8 × 10-10 M, neutral
Answer:
A. 5.5 × 10⁻¹⁰ M, acidic
Explanation:
Step 1: Given data
Concentration of H₃O⁺: 1.8 10⁻⁵ M
Step 2: Calculate the concentration of OH⁻
We will use the ionic product of water.
Kw = 1.0 × 10⁻¹⁴ = [H₃O⁺] × [OH⁻]
[OH⁻] = 1.0 × 10⁻¹⁴/[H₃O⁺] = 1.0 × 10⁻¹⁴/1.8 10⁻⁵ = 5.5 × 10⁻¹⁰ M
Step 3: Determine if the solution is acidic, basic or neutral
If [H₃O⁺] > 10⁻⁷ M, the solution is acidic.If [H₃O⁺] = 10⁻⁷ M, the solution is neutral.If [H₃O⁺] < 10⁻⁷ M, the solution is basic.Then, the solution is acidic.
PLSSS HELP ASAP!!!!!!!!
Answer:
i-dk but A seems most logical to me
Explanation:
What product(s) would be formed when these are the reactants? BaF2 + Cl2
0.500 mole of copper(II) sulfate contains
moles of O.
Answer:
2 mol
Explanation:
There are 4 mols of O per one sulfate so since there is only one sulfate you simply times 4 by .5 to get the number of mol
Is anyone good at chemistry if so can someone help me please ?
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Since pH + pOH = 14, given a pOH of 4.53, our pH would be 14 - 4.53 = 9.47. And since the pH is greater than 7, this solution is basic. So, the correct answer choice would be D.
How was the position of planet Uranus predicted?
Upon studying the orbit of Uranus more closely, astronomers realized its orbit was being affected by the presence of another very large mass - so the hunt was on for another large planet. He sent his prediction to the Astronomer Royal, Sir George Airy, who passed it on to an 'observer'.
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The position of Uranus was predicted by determining the position of a larger mass ( Neptune ) exerting a gravitational push on Uranus
Uranus is the 7th planet in the galaxy it was initially discovered with the aid of a telescope by an astronomer whom initially thought it was a star.
The position of Uranus was predicted when an astronomer ( John Couch Adams ) and his colleague predicted the gravitational effect on Uranus from another larger mass ( Neptune ). they discovered the position of the larger mass affecting the orbit of Uranus and the position of this larger mass ( Neptune ) was used to predict the position of Uranus in the galaxy.
Hence we can conclude that the position of Uranus was predicted by determining the position of a larger mass ( Neptune ) exerting a gravitational push on Uranus
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21 Organs consist of cells and tissues that have been adapted to perform a specific function in living organisms. The stomach is a muscular organ that is located on the left side of the upper abdomen. The stomach secretes acid and enzymes that help in the digestion of food. In simple terms, the stomach is a digestive sac. Even though the stomach has an important role in food digestion, it cannot perform the process all on its own. It depends on other organs such as the salivary glands, esophagus, liver, and intestines to help complete the process. Each organ has its own specific job, but together they make up an organ system. An organ system is a group of organs that work together to perform one or more functions. Which of the following describes the role of the immune system in the body? A. It gets rid of wastes that the body produces. B. It uses electrical signals to control body functions. C. It uses chemical messages to control body functions. D. It gets rid of pathogens that invade the body.
Answer:
The correct answer is - D. It gets rid of pathogens that invade the body.
Explanation:
Like all other organ systems, the immune system is an organ system that involves several special organs that helps in fighting any foreign object or infection that invades our body. This organ system produces specific cells or chemicals to fight or kill the microbes, and unnatural change takes place in the body.
The organs involved in the immune system are lymphocytes or white blood cells, the complement system, antibodies, the lymphatic system the thymus, bone marrow, and the spleen.
All these combinedly helps in fighting, killing the microbes or infections that occur in the body, and correct the physiological changes that occur in the body to get rid of pathogens that invade the body.
If I contain 2 moles of gas in a container with a volume of 30 liters and at a temperature of 337 K, what is the pressure inside the container?
Answer:
1.84
Explanation: just input the value into the formula pv=nrt
p*30=2*0.08206*337 then divide both sides by 30 and get 1.84
number of atoms per unit cell in face centred cube is
Answer: 4 atoms is the answer. I hope it helped you.
Explanation:
Please answer this question correctly
Answer:
a d c a b b
Explanation:
22 Which of the following statements is true for all loving organisms? A. All living organisms are made of one or more cells with a cellular membrane and have a cell wall. B. All living organisms are made of one or more cells with a cellular membrane and have a nucleus. C. All living organisms are made of one ore more cells with a cellular membrane and genetic material. D. All living organisms are made of one or more cells with a cellular membrane and have chloroplast
Answer:
C
Explanation:
Ape-x
(d) Other
sugar molecules become
_____ and are carried away from the crystal.
the force of attraction is
Answer:
liquid
Explanation:
defiantly
The half-life of I-37 is 8.07 days. If 25 grams are left after 40.35 days, how many grams were in the original sample?
Answer:
800 g
Explanation:
We can express the decay of I-37 using the formula:
Final Mass = Initial Mass * [tex]0.5^{\frac{Time}{Half-Life} }[/tex]We input the data:
25 g = Initial Mass * [tex]0.5^{(\frac{40.35}{8.07})}[/tex]And solve for Initial Mass:
25 g = Initial Mass * [tex]0.5^{5}[/tex]25 g = Initial Mass * 0.03125Initial Mass = 800 gMeaning that out 800 grams of I-37, only 25 will remain after 40.35 days.
Why is there not a constant molar volume for solids and
liquids?
a Solid and liquid particles are packed close together,
b The densities of solids and liquids are variable.
с
The volume of a solid or a liquid has very little
empty space.
d All of the above
Answer:
all of the above
Explanation:
i got the answer right on cK-12
A 16 gram sample of O2(g) fills a container at STP.
What volume is the container?
Answer:
V = 11.2 L
Explanation:
Hello there!
In this case, according to the ideal gas equation:
[tex]PV=nRT[/tex]
It is possible to compute the volume as shown below:
[tex]V=\frac{nRT}{P}[/tex]
Whereas the moles are computed are computed given the mass and molar mass of oxygen:
[tex]n=16g*\frac{1mol}{32g} =0.5mol[/tex]
Now, since the STP stands for a temperature of 273.15 K and a pressure of 1 atm, the resulting volume is:
[tex]V=\frac{0.5mol*0.08206\frac{atm*L}{mol*K}*273.15K}{1atm}\\\\V=11.2L[/tex]
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What can be different between products and reactants in a balanced equation?
a) The total mass of products and reactants
b) The total moles of each element present in the reactants and in the products.
c) The number of molecules in the reactants and in the products
Answer:
b) The total moles of each element present in the reactants and in the products.
Explanation:
Hello there!
In this case, since the law of conservation of mass is used to realize that the mass, atoms and molecules of all the species involved in a chemical reaction must be the same at both reactants and products, we can see that a and c stand for those that must be equal; thus, we infer that the moles can be different as they stand for the amount of substance which is related to the mass via molar masses. Therefore, the answer would be b) The total moles of each element present in the reactants and in the products.
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what is the speed of the electromagnetic waves please solve using correct units ill give brainliest.
Answer:
3 m
Explanation:
We'll begin by converting 99.9 MHz to Hz. This can be obtained as follow:
1 MHz = 10⁶ Hz
Therefore,
99.9 MHz = 99.9 MHz × 10⁶ Hz / 1 MHz
99.9 MHz = 99.9×10⁶ Hz
Finally, we shall determine the wavelength. This can be obtained as follow:
Frequency (f) = 99.9×10⁶ Hz
Velocity (v) = 3×10⁸ m/s
Wavelength (λ) =?
Velocity = wavelength × frequency
v = λf
3×10⁸ = λ × 99.9×10⁶
Divide both side by 99.9×10⁶
λ = 3×10⁸ / 99.9×10⁶
λ = 3 m
Thus, the wavelength of the electromagnetic wave is 3 m.
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What are characteristics of absorption spectra? Check all that apply.
Light is absorbed, which produces characteristic lines.
| Light is emitted, which produces characteristic lines.
Lines are dark on a visible light background.
Lines are brightly colored on a black background.
Lines are produced by electrons being excited.
Lines are produced from electrons returning to a lower energy level.
Answer:
Light is absorbed, which produces characteristic lines.
Lines are dark on a visible light background.
Lines are produced by electrons being excited.
Explanation:
Edg
The characteristics of absorption spectra light is absorbed, which produces characteristic lines, lines are dark on a visible light background and Lines are produced by electrons being excited.
What is absorption spectra?The term "absorption spectroscopy" applies to spectroscopic methods that assess how much radiation interacts with a sample and is absorbed as a proportion of frequency or wavelength. The sample takes in photons, meaning energy, from the emitting field.
What are electrons?The electron would be a subatomic particle with a negative one fundamental charge electric charge. Due to their lack of components or substructure, electrons, which have become part of the lepton particle family's first generation, could be typically regarded to be elementary particles.
The percentage of incoming electromagnetic energy that a material absorbs across a variety of frequencies is displayed in the material's absorption spectrum. In a way, an emission spectrum would be the converse of an absorption spectrum.
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Which product forms from the synthesis reaction between lithium (Li) and oxygen (O)?
A. Li2O
B. LiO
C. LiO2
D. Li2O2
Answer:
A Li2O
Explanation:
Li has a 1+ charge and O has a 2- charge so to balance the charges there needs to be 2 Li for every 1 O
The product forms from the synthesis reaction between lithium (Li)and oxygen (O) is Li₂O. The correct option is A.
What is synthesis reaction?
Synthesis reaction is the reaction when two or more products combine to form a single product.
An example of a synthesis reaction is the combination of sodium (Na) and chlorine (Cl) to produce sodium chloride (NaCl).
Thus, the correct option is A. Li2O.
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_____ are the 14 transition metals that follow
lanthanum in the periodic table.
What is the blank
Answer:
Lanthanide or Lanthanides
Explanation:
sorry if this isent right, but i hope it helps
There are various kind of elements that are present in periodic table. Some elements are harmful, some are radioactive, some are noble gases. Therefore the correct option is Lanthanides and actinides.
What is periodic table?Periodic table is a table in which we find elements with properties like metals, non metals, metalloids and radioactive element arranges in increasing atomic number.
Periodic table is divided into blocks as s block, p block ,d block and f block. There are total two periods of f block elements. The one that comes in 6th period is called Lanthanides and one which is in 7th period is called actinides. Lanthanides and actinides are called inner transition element and contains 14 elements.
Therefore the correct option is Lanthanides and actinides.
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Please disregard this
well i need points
Explanation:
thanks
If 75 g. of Potassium Chloride (ionic compound) is dissolved in 250 grams of
water, what will be the freezing point of the solution? Kf = 1.86
Answer:
[tex]T_{f,sol}=-15.0\°C[/tex]
Explanation:
Hello there!
In this case, for these problem about the colligative property of freezing point depression, it is possible set up the following equation:
[tex]T_{f,sol}-T_{f,water}=-i*m*Kf[/tex]
Whereas the van't Hoff's factor, i, is 2 since KCl is ionized in two ions (K+ and Cl-); and the molality (m) of the solution is computed by:
[tex]m=\frac{75g*\frac{1mol}{74.55g} }{250g*\frac{1kg}{1000g} } \\\\m=4.02mol/kg[/tex]
Thus, since the freezing point of water (ice) is 0°C, we obtain the following freezing point of the solution by plugging in:
[tex]T_{f,sol}=-(2)(4.02mol/kg)(1.86\°C/mol*kg)\\\\T_{f,sol}=-15.0\°C[/tex]
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5.50 L of a 0.190 M CaCl2M CaCl2 solution
How do you find Grams?
Answer:
115.891
Explanation:
Molarity is equal to moles/liters so to get moles we multiply molarity by liters, after this we multiply the moles by the total atomic weight of the compound to get grams