Answer:
i think b is the answer hope this helps:))
Calculate the specific heat in J/(g·ºC) of an unknown substance if a 2.50-g sample releases 12.0 cal as its temperature changes from 25.0ºC to 20.0ºC. ________J/(g·°C)
The specific heat of an unknown substance is 0.96 J/(g·ºC).
What is the specific heat capacity?The specific heat capacity of a substance can be described as the quantity of heat needed to raise the temperature in one unit of substance by 1 degree Celcius.
Whenever the heat is lost or absorbed there is a change in the temperature of the substance:
Q = mCΔT
Given, the amount of energy released, Q = 12 cal
The initial temperature of the substance = 25.0ºC
The final temperature of the substance = 20.0ºC
The change in the temperature of a substance, ΔT = 25 -20 = 5°C
The mass of the substance, m = 2.50 g
We have to find the specific heat capacity of an unknown substance.
12 cal = 2.50 g × C × 5°C
C = 0.96 J/(g·ºC)
Therefore, the specific heat capacity of an unknown substance is equal to 0.96 J/(g·ºC).
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The amount of heat needed to raise a substance's temperature by one degree Celsius per gram is known as specific heat. The specific heat in J/(gºC) of an unknown substance is 0.96 J/gºC.
The amount of heat needed to increase the temperature of the entire substance by one degree is the heat capacity of a substance. Specific heat capacity is what is used when the substance's mass is equal to one.
The hydrogen bonds in water, which account for its high specific heat.
The expression used to calculate the specific heat capacity is:
Q = mcΔT
Here Q = 12 Cal
m = 2.50 g
T₁ = 25.0ºC
T₂ = 20.0ºC
ΔT = 5°C
12 cal = 2.50 g × c × 5°C
c = 0.96 J/gºC
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Calculate the freezing point and boiling point of each aqueous solution, assuming complete dissociation of the solute.
a. 0.100 m K2S
b. 21.5 g of CuCl2 in 4.50 * 102 g water
c. 5.5% NaNO3 by mass (in water)
The freezing points of each of the solutions are as follows;
0.100 m K2S - - 0.558oC
21.5 g of CuCl2 in 4.50 * 102 g water - -2oC
5.5% NaNO3 by mass (in water) - - 2.6oC
What is freezing point?The freezing point is the point at which liquid changes to solid. Let us now look at the freezing point of each solution.
a)
Since;
ΔT = K m i
K = 1.86 oC m-1
m = 0.100 m
i = 3
ΔT = 1.86 oC m-1 * 0.100 m * 3 = 0.558oC
Freezing point = 0oC - 0.558oC = - 0.558oC
b) Number of moles of CuCl2 = 21.5 g/134.45 g/mol = 0.16 moles
molality = 0.16 moles/0.45 Kg = 0.36 m
ΔT = K m i
ΔT = 1.86 oC m-1 * 0.36 m * 3 = 2oC
Freezing point = 0oC - 2 = -2oC
c) Number of moles of NaNO3 = 5.5g/85 g/mol = 0.065 moles
molality of the solution = 0.065 moles/0.0945 Kg = 0.69 m
ΔT = 1.86 oC m-1 * 0.69 m * 2 = 2.6oC
Freezing point = 0oC - 2.6oC = - 2.6oC
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Which of the following UV rays has the highest energy that damages your skin the most?
A. UVA
B. UVB
C. X-ray
D. Infrared (IR)
What mass of water is in a calorimeter where 225.0 J of heat are
transferred to the water from a heated piece of metal and the
temperature of the water is increased by 4.00°C?
Answer:
22.25 °C
Explanation:
Determine the final temperature when a 25.0 g piece of iron at 85.0 °C is placed into 75.0 grams of water at 20.0 °C.
What are two relatively unique physical properties of water? What impact do these properties have on life on Earth?
Answer:
Polar molecule. A neutral, or uncharged molecule that has an asymmetric internal distribution of charge, leading to partially positive and partially negative regions
Cohesion The attraction of molecules for other molecules of the same kind
Adhesion The attraction of molecules for other molecules of a different kind
Density The mass per unit volume of a substance
Specific heat capacity The amount of heat needed to raise the temperature of one gram of a substance by one degree Celsius
Heat of vaporization The amount of energy needed to change one gram of a liquid substance to a gas at constant temperature
Polar substance. a molecule that is neutral or uncharged but has an asymmetric internal charge distribution that produces both positive and negative regions.
What are Physical properties ?Cohesion molecules' attraction to other molecules of the same sort. Adhesion the pull of certain molecules toward others of a different type
Density a substance's mass per unit volume particular heat capacity The amount of heat required to increase a substance's temperature by one degree Celsius in one gram
Vaporization-related heat energy required to convert one gram of a liquid material into a gas at a fixed temperature.
Therefore, Polar substance. a molecule that is neutral or uncharged but has an asymmetric internal charge distribution that produces both positive and negative regions.
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2AI(NO3)3 + 3Na2CO3 → Al2(CO3)3(s) + 6NaNO3
What is the ratio of moles of AI(NO3)3 to moles Na2CO3?
The ratio of moles of AI(NO3)3 to moles Na2CO3 in the reaction is 2:3
In the reaction 2 moles of AI(NO3)3 reacted with 3 moles Na2CO3 so the ratio of the moles is 2 is to 3 represented as 2:3
hope it helps
Becquerel placed photographic paper in a drawer with some radioactive rocks and discovered that the amount of exposure on the paper was proportional to the amount of uranium that was present in the rocks. True False
Becquerel did not discover that the amount of exposure on the paper was proportional to the amount of uranium that was present in the rocks
What is radioactivity?The phenomenon of radioactivity was discovered by the French scientist Henri Becquerel in 1896 when he placed photographic paper in a drawer with some radioactive rocks.
We have to note that Becquerel did not discover that the amount of exposure on the paper was proportional to the amount of uranium that was present in the rocks hence the stetement is false.
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A sample of calcium fluoride was decomposed into the constituent elements. If the sample produced 625 mg of calcium, how many grams of fluorine were formed?
The mass of fluorine that were formed is 592 mg
StoichiometryFrom the question, we are to determine the mass of fluorine formed
First, we will write the balanced chemical equation for the decomposition reaction
The balanced chemical equation for the reaction is
CaF₂ → Ca + F₂
This means
1 mole of calcium fluoride decomposes to give 1 mole of calcium and 1 mole of fluorine
Now, we will determine the number of moles of calcium produced
From the given information,
Mass of calcium produced = 625 mg = 0.625 g
Using the formula,
[tex]Number\ of \ moles =\frac{Mass}{Atomic\ mass}[/tex]
Atomic mass of calcium = 40.078 g/mol
Then,
Number of moles of calcium produced = [tex]\frac{0.625}{40.078}[/tex]
Number of moles of calcium produced = 0.01559 mole
Since
1 mole of calcium fluoride decomposes to give 1 mole of calcium and 1 mole of fluorine
Then,
0.01559 mole of calcium fluoride will decompose to give 0.01559 mole of calcium and 0.01559 mole of fluorine
∴ Number of mole of fluorine formed was 0.01559 mole
Now, for the mass of fluorine formed
Using the formula,
Mass = Number of moles × Molar mass
Molar mass of fluorine = 38 g/mol
Then,
Mass of fluorine formed = 0.01559 × 38
Mass of fluorine formed = 0.59242 g
Mass of fluorine formed = 592.42 mg
Mass of fluorine formed ≅ 592 mg
Hence, the mass of fluorine that were formed is 592 mg.
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Which of the following is not an example of a modified silicate?
Ceramics
Glass
Cement
Quartz
Quartz is not regarded as an example of a modified silicate.
What is Quartz?This is defined as a hard, crystalline mineral composed of silica with a tetrahedral shape. Silica is also referred to as Silicon dioxide(SiO₂).
This type of mineral is a naturally occurring crystal and isn't a modified silicate but the rest can be modified using their respective constituents thereby making option D the most appropriate choice.
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When a 21.2 mL sample of a 0.411 M aqueous hydrofluoric acid solution is titrated with a 0.371 M aqueous barium hydroxide solution, what is the pH after 17.6 mL of barium hydroxide have been added
For a 21.2 mL sample of a 0.411 M aqueous hydrofluoric acid solution, the pH after 17.6 mL of barium hydroxide has been added is mathematically given as
pH=3.332
What is the pH after 17.6 mL of barium hydroxide has been added?Generally, the equation for the mole of HF is mathematically given as
mole of HF=molarity*volume
Therefore
mole of HF=0.361*19.2
mole of HF=6.931mmol
The chemical equation
HF+kOH⇆KF+H2O
Therefore
pH=pKa+log(Kf/HF)
pH=3.15+log(6.931*53.6/53.6*4.558)
pH=3.332
In conclusion, The pH
pH=3.332
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When .080 moles of propane burn at STP, what volume of carbon dioxide is produced?
The answer is 5.4 L (I NEED THE STEPS)
The volume of carbon dioxide produced is : 5.4 L
Given data:
moles of propane = 0.080 moles
Determine the volume of Carbon dioxide producedThe chemical reaction
C₃H₈ + 5O₂ ---- > 3CO₂ + 4H₂O
From the reaction
I mole of C₃H₈ = 3CO₂
0.080 moles of C₃H₈ = 3 * 0.080 = 0.24
Applying the equation below to determine the volume of CO₂
Pv = nRT
= 0.24 * R * T
v = ( 0.24 * 8.314 * 273 ) / 1 atm
= 544.7 ml = 5.4 L
Hence we can conclude that The volume of carbon dioxide produced is : 5.4 L
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can u help me with this
Answer:
c
Explanation:
the reason is because your a homosiejenenddj
What state of matter has the most kinetic energy?
A gas
B liquid
C solid
Answer:
gaseous state.
Explanation:
that's the answer
what mass of water must be added to 0.50 mol of glucose to make a solution of 25 percent by mass? the molar mass of glucose is 180 g/mol. SHOW WORK PLSS.
Answer:
270 g of water
Explanation:
what is the empirical formula of a cpd containing 60.0%of sulfur 40.0% oxygen by mass
Answer:
n S = 60 32 = 1.875 , n_S=\tfrac{60}{32}=1.875, nS=3260=1.875, n O = 40 16 = 2.5.
Explanation:
Decomposition of hydrogen peroxide: 2H2O2 --> O2(g) + 2H2O(l) How many molecules of water are produced from the decomposition of 3.4g of hydrogen peroxide, H2O2?
Answer:
Explanation:
You have the equation. Now change the 3.4 g H2 to moles. moles = grams/molar mass
3.4 g/2.016 = 1.686 moles.
Now using the coefficients in the balanced equation, convert moles H2O2 to moles H2O.
1.686 moles H2 x (2 moles H2O/2 moles H2O2) = 1.686 x (2/2) = 1.686 x (1/1) = 1.686 moles H2O.
Now you know that 1 mole of water is composed of 6.022 x 10^23 molecules. So
1.686 moles H2O x (6.022 x 10^23 molecules H2O/1 mole H2O) = ?? molecules.
There are 7 named classes of hazardous materials.
O True
O False
False, there are 9 named classes of hazardous materials.
What are hazardous materials?Hazardous materials are substances or chemicals that pose a health hazard, a physical hazard, or harm to the environment.
There are 9 hazardous substances symbols you need to know: flammable, oxidising, explosives, gas under pressure, toxic, serious health hazard, health hazard, corrosive and environmental hazard.
Hence, the statement is false.
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How many grams of aluminum will be deposited by 0.1F? (Al=27) a.0.3g b. 0.9. c. 9.0g. d. 2.7g
Based on the charge on the aluminium ion, 0.9 g of aluminium are deposited by 0.1 F of electricity.
What is electrolysis?Electrolysis is the decomposition of a substance known as an electrolyte when electric current is passed through it.
The mass and hence moles an electrolyte deposited when current is passed through it depends on the charge on the ion.
Aluminium ion has a charge of +3 and requires 3F of electricity to deposit 1 mole or 27 g of aluminium
0.1 F will discharge = 0.1/3 × 27 g of aluminium
mass of aluminium deposited = 0.9 g of aluminium.
Therefore, 0.9 g of aluminium are deposited by 0.1 F of electricity.
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what does rows represent on the periodic table
Answer:
Rows on the periodic table represents a period, which is the number of energy levels or rings. It is the last shell which valence electrons are on.
For example the first row waas Hydrogen and Helium which each have one energy level.
The esecond row has Carbon and Oxygen which has two energy level.
The third row has Sodium which has three energy levels and so on.
- If you have bottle filled with Sulfur Hexafluoride and there are 1.00 L of the liquid with a density of 1.60 g/mL, how many moles of the liquid are present?
Answer:
About 11.0 moles.
Explanation:
We are given a bottle filled with 1.00 L of sulfur hexafluoride (SF₆) and we want to determine the number of moles of the liquid that is present.
First, determine its mass with the given density:
[tex]\displaystyle \begin{aligned}\rho & = \frac{m}{V} \\ \\ m & = \rho V \\ \\ & = \left(\frac{1.60\text{ g}}{\text{mL}}\right)(1.00\text{ L})\left(\frac{1000\text{ mL}}{1\text{ L}}\right) \\ \\ & = 1.60\times 10^3 \text{ g}\end{aligned}[/tex]
The molecular weight of SF₆ is 146.07 g/mol. Hence:
[tex]\displaystyle 1.60\times 10^3\text{ g SF$_6$} \cdot \frac{1\text{ mol SF$_6$}}{146.07\text{ g SF$_6$}} = 11.0\text{ mol SF$_6$}[/tex]
Therefore, about 11.0 moles of sulfur hexafluoride is present.
An unidentified covalent molecular compound contains only carbon, hydrogen, and oxygen. When 7.40 mg of this compound is burned, 17.80 mg of CO2 and 2.08 mg of H2O are produced.
The freezing point of camphor is lowered by 26.4°C when 3.044 g of the compound is dissolved in 18.00 g of camphor (Kf = 40.0°C kg/mol).
What is the molecular formula of the unidentified compound?
Choose appropriate coefficients in the molecular formula below.
C H O
The molecular formular shows all the atoms in the compound. The molecular formula of the compound is C15H10O5.
What is molecular formula?The molecular formula is the formula of the compound that shows the total number of atoms in a compound.
We know that;
ΔT = K m i
ΔT = 26.4°C
K = 40.0°C kg/mol
m = ?
i = 1
26.4°C = 40.0°C kg/mol * m * 1
m = 26.4°C/40.0°C kg/mol = 0.66 m
We know that
m = mass/molar mass ÷ mass of solvent(in Kg)
Let the molar mass be MM
m = 3.044 g/MM ÷ (18 * 10^-3 Kg)
0.66 m = 3.044 g/0.018MM
0.66 m * 0.018MM = 3.044 g
MM = 3.044 g/0.66 m * 0.018
MM = 256 g/mol
Now;
Mass of C = 17.80 * 10^-3/44 * 12 = 0.00485 g
Moles of C = 0.00485 g/12 g/mol = 0.0004 moles
Mass of H = 2.08 * 10^-3/18 * 2 = 0.0002 g
Moles of H = 0.0002 g/1 g/mol = 0.0002 moles
Mass of O = [7.40 * 10^-3 - (0.00485 + 0.0002)] = 0.00235 g
Moles of O = 0.00235 g/16 g/mol = 0.000147 moles
Divide through by the lowest number of moles;
C - 0.0004/0.000147 H - 0.0002/0.000147 O - 0.000147 /0.000147
C - 3 H - 2 O - 1
The empirical formula is C3H2O
So;
[3(12) + 2(1) + 1(16)]n = 256
[36 + 2 + 16]n = 256
n = 5
Molecular formula = C15H10O5
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If a watershed suddenly receives a great deal of rainfall, what will happen to its wetlands and rivers?
Answer:
Depending on the actual amount of water, it's going to overfill.
Explanation:
If your watershed is already one that has a lot of water and is always filled, it's likely that your wetlands and rivers will start to overfill, causing a form of flooding.
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I hope this helps!
-No one
PROBLEM SETS: %BY MASS, % BY VOLUME, MOLARITY, MOLALITY (show your solution)
1. What is the molarity of a solution in which 0.850 grams of ammonium nitrate are dissolved in 345 mL of solution?
2. Calculate the molality of a solution of 13.5g of KF dissolved in 250. g of water.
3. Calculate the molality of a solution containing 16.5 g of dissolved naphthalene (C10H8) in 54.3 g benzene (C6H6).
4. What is the mass percent of each component in the mixture formed by adding 12 g of calcium sulfate, 18 g of sodium nitrate, and 25 g of potassium chloride to 500 g of water?
5. A solution is made by dissolving 125 g of sodium chloride in 1.5 kg of water. What is the percent by mass?
6. What is the percent by volume of a solution formed by added 15 L of acetone to 28 L of water?
The concentration of a substance can be expressed using molarity, molality or percent.
What is concentration?The term concentration has to do with the amount of substance present in solution. Now let us solve the problems individually;
a) Number of moles = 0.850 grams/80 g/mol = 0.011 moles
molarity = 0.011 moles/345 * 10^-3 L = 0.032 M
b) Number of moles = 13.5g /58 g/mol = 0.23 moles
molality = 0.23 moles/250 * 10^-3 Kg = 0.92 m
c) Number of moles = 16.5 g/128 g/mol = 0.13 moles
molality = 0.13 moles/54.3 * 10^-3 Kg =2.39 m
d) Total mass present = 12 g + 18 g + 25 g + 500 g = 555 g
mass percent of calcium sulfate = 12 g/555 g * 100/1 = 2.2 %
mass percent of sodium nitrate = 18 g/ 555 g * 100/1 = 3.2 %
mass percent of potassium chloride = 25 g / 555 g * 100/1 = 4.5%
mass percent of water = 500 g / 555 g * 100/1 =90.1%
e) Total mass present = 125 g + 1500g = 1625 g
Mass percent of NaCl = 125 g/1625 g * 100/1 = 7.7%
f) Total volume of solution = 15 L + 28 L = 43 L
percent by volume of acetone = 15 L/43 L * 100/1 = 34.9%
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A sample of methane gas contains 3.62x10^29 atoms of hydrogen. What is the mass of the sample?
The mass of the sample to methane that contains 3.62×10²⁹ atoms of hydrogen is 4810631.24 g
Avogadro's hypothesis6.02×10²³ atoms = 1 mole of Hydrogen
How to determine the mass of Hydrogen1 mole of Hydrogen = 2 g
Thus,
6.02×10²³ atoms = 2 g of Hydrogen
Therefore,
3.62×10²⁹ atoms = (3.62×10²⁹ × 2) / 6.02×10²³
3.62×10²⁹ atoms = 1202657.81 g of Hydrogen
How to determine the mass of methane 1 mole of methane, CH₄ = 12 + (4×1) = 16 gMass of H in 16 g of CH₄ = 4 × 1 = 4 gThus,
4 g of Hydrogen is present in 16 g of methane.
Therefore,
1202657.81 g of Hydrogen will be present in = (1202657.81 × 16) / 4 = 4810631.24 g of methane
Thus, we can conclude that the mass of the sample of methane is 4810631.24 g
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At 25°C the vapour pressure of pure pentane is 511 torr and that of hexane is 150. torr.
What is the mole fraction of pentane in a pentane-hexane solution that has a vapour pressure of 383 torr at 25°C?
ANSWER IS 6.45×10-1
QUESTION: What is the mole fraction of hexane in the vapour that is in equilibrium with this solution?
(Assume ideal gas behaviour.)
Based on the vapor pressure of the pure substances, the mole fraction of pentane is 0.45 and mole fraction of hexane at equilibrium is 0.60.
What is vapor pressure of a liquid?Vapor pressure of of a liquid is the pressure that is excreted on the walls of a sealed vessel by the molecules of the liquid that have been converted to gaseous phase.
TO determine the mole fraction of pentane in the solution, we use the vapor pressure of the pure substances.
Let the mole fraction of pentane in the mixture be X.
The mole fraction of hexane will be 1 - X
The vapor pressure of the solution = (mole fraction of pentane × vapor pressure of pentane) + (mole fraction of hexane × vapor pressure of hexane)Vapor pressure of solution = 383 torr
(mole fraction of pentane × vapor pressure of pentane) + (mole fraction of hexane × vapor pressure of hexane) = 383 torr
X × 511 + (1 - X) × 150 = 383
511X - 150X + 150 = 383
511X = 233
X = 0.45
Also , at equilibrium, the vapor pressure of pentane = 0.45 × 511 = 230 torr
mole fraction of hexane in the vapor that is in equilibrium with this solution = 230/383
mole fraction of hexane at equilibrium = 0.60
Therefore, the mole fraction of pentane is 0.45 and mole fraction of hexane at equilibrium is 0.60.
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Write an equation that represents the action in water of hypoiodous acid ( HOI ) as a Brønsted–Lowry acid.
Taking into account the Brønsted-Lowry acid-base theory, the reaction between hypoiodous acid and water is:
HOI + H₂O ⇄ OI⁻ + H₃O⁺
Brønsted-Lowry acid-base theoryThe Brønsted-Lowry acid-base theory (or the Brønsted-Lowry theory) identifies acids and bases based on whether the species accepts or donates protons or H⁺.
According to this theory, acids are proton donors while bases are proton acceptors. That is, an acid is a species that donates an H⁺ proton while a base is a chemical species that accepts an H⁺ proton from the acid.
So, reactions between acids and bases are H⁺ proton transfer reactions, causing the acid to form its conjugate base and the base to form its conjugated acid by exchanging a proton.
Reaction between hypoiodous acid and waterIn this case, the reaction between hypoiodous acid and water is:
HOI + H₂O ⇄ OI⁻ + H₃O⁺
where HOI acts as an acid because it donates a potron, while water acts as a base because it accepts the proton donated by HOI.
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The correct IUPAC name for 2-isopropylbutane is: a) 2-ethylpentane b) 2,3-dimethylpentane c) 2-methylhexane d) 3-methylhexane
Answer:
a
Explanation:
On drawing the structure, the most Carbon atoms in a row is 5
⇒ pentaneThe remaining two carbon atoms are connected to the 2nd carbon atom
2-ethylIUPAC name is :
2-ethyl + pentane2-ethylpentaneyou find a mysterious white powder in your kitchen. it could be cream of tartar (pH=5), sugar (pH=7), baking soda (pH=8), or drain cleaner (pH=14). explain which pH indicator(s) you would use to determine the unknown substance.
The pH indicators that would be used to determine the unknown substance are :
Litmus Methyl orangePhenol RedpH IndicatorsThe pH indicators that can be used to identify the mysterious white powder in the kitchen must be an acid-base indicator such as Litmus or other form of effective pH indicators like methyl orange and Phenol red.
The pH value of the substance as indicated by the acid-base indicators will help to determine what the mysterious white powder is based on the varying pH of the substances resembling the white powder.
Hence we can conclude that The pH indicators that would be used to determine the unknown substance are :Litmus , Methyl orange, Phenol Red.
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pls help me with this
Answer:
silver
5/20
=0.25.................
Answer:
C
Explanation:
Aluminum density = 0.5
Iron density = 2
Gold density = 1
Silver density = 0.25
The smallest value is 0.25 hence silver has less density.
If you were to classify a newly discovered animal, what would you want to know first?
Does it live on land or in the sea?
Does it have a backbone?
Does it have hair?
Does it have vascular tissue?
Answer:
A
Does it live on land or sea.
Answer:
C:
I would check that does it have hair or not because hair provides info about the DNA which can help me if that specific animal has evolved from DNA of any other animal..
Hope it helped you.