Answer:
1.62
Explanation:
From the given information:
number of moles of benzamide [tex]=\dfrac{70.4 \ g}{121.14 \ g/mol}[/tex]
= 0.58 mole
The molality = [tex]\dfrac{mass \ of \ solute (i.e. \ benzamide )}{mass \ of \ solvent }[/tex]
[tex]= \dfrac{0.58 }{0.85 }[/tex]
= 0.6837
Using the formula:
[tex]\mathbf {dT = l \times k_f \times m}[/tex]
where;
dT = freezing point = 27
l = Van't Hoff factor = 1
kf = freezing constant of the solvent
∴
2.7 °C = 1 × kf × 0.6837 m
kf = 2.7 °C/ 0.6837m
kf = 3.949 °C/m
number of moles of NH4Cl = [tex]\dfrac{70.4 \ g}{53.491 \ g /mol}[/tex]
= 1.316 mol
The molality = [tex]\dfrac{1.316 \ mol}{0.85 \ kg}[/tex]
= 1.5484
Thus;
the above kf value is used in determining the Van't Hoff factor for NH4Cl
i.e.
9.9 = l × 3.949 × 1.5484 m
[tex]l = \dfrac{9.9}{3.949 \times 1.5484 \ m}[/tex]
l = 1.62
helpppp nowwww plssss!!!
Answer: B
Explanation:
If the flour mixture is then taken and put into the oven for about 20 minutes, it turns into something very tasty. What kind of change has happened now?
Answer:
physical change
Explanation:
i got the same question sorry for the late response but that's the answer good luck
Which of the following is a list of the minimum amount of data needed for determining the molar enthalpy of solution of KCl(s) in pure H2O(1) ? (Assume that the KCl(aq) has the same specific heat capacity as pure water and that the initial temperatures of the KCl(s) and the water are the same.)
(A) Mass of KCl(s), initial temperature of the water, and final temperature of the solution
(B) Mass of H20, initial temperature of the water, and final temperature of the solution
(C) Mass of KCl(s), mass of H20, initial temperature of the water, and final temperature of the solution
(D) Mass of KCl(s), mass of H20, initial temperature of the water, final temperature of the solution, and atmospheric pressure
Answer:
(C) Mass of KCl(s), mass of H20, initial temperature of the water, and final temperature of the solution
Explanation:
molar enthalpy of solution of KCl(s) is heat evolved or absorbed when one mole of KCl is dissolved in water to make pure solution . The heat evolved or absorbed can be calculated by the following relation.
Q = msΔt where m is mass of solution or water , s is specific heat and Δt is change in temperature of water .
So data required is mass of water or solution , initial and final temperature of solution , specific heat of water is known .
Now to know molar heat , we require mass of solute or KCl dissolved to know heat heat absorbed or evolved by dissolution of one mole of solute .
The correct option is option C.
To determine the molar enthalpy of the solution of [tex]Kcl(s)[/tex] is pure [tex]H_2O(l)[/tex]
We need to know that the,
grams of [tex]Kcl(s)[/tex] grams of [tex]H_2O[/tex] Initial temperature of [tex]H_2O[/tex] The final temperature of the solution.Learn More:https://brainly.com/question/25758173
If you have 3.5 L of He to blow up balloons... at STP...
a) How many moles of He do you have?
b) How many grams of He do you have?
Answer:
B
Explanation:
Which statement about Niels Bohr's atomic model is true?
O Higher orbits have lower energies.
O Each orbit has a specific energy level.
O Electrons can exist in any energy level.
O Orbits close to the nucleus have no energy.
Answer:
O Each orbit has a specific energy level.
Explanation:
Neils Bohr put forward his own model of the atom based on the quantum mechanics originally developed by Planck.
He assumed the Rutherford's model and suggested that the extranuclear part consists of electrons in specific spherical orbits around the nucleus.
The orbits/energy level are the permissible through which the electrons can move through.
His concept is based the concept that the electron can move round the nucleus in certain permissible orbitss
WORTH 40 POINTS HELLPPPP
What class of element is Astatine (At)?
Answer:
halogen.
nonmetal.
Explanation:
PLZ HELP ASAP WILL GIVE BRAINLIST
2AlCl3 + 2Al + 3Cl2
If 20.0 g of aluminum chloride are decomposed, how many molecules of chlorine gas are produced?
A )6.63 x 1022 molecules CI
B )2.70 x 1023 molecules Cl2
C )1.35 x 1023 molecules Cl2
D )9.42 x 1023 molecules Cl2
Explanation:
Molar mass of AlCl3 = 133.34g/mol
Moles of AlCl3 used
= 20.0g / (133.34g/mol) = 0.150mol
Mole Ratio of AlCl3 to Cl2 = 2 : 3,
Moles of Cl2 produced
= 0.150mol * (3/2) = 0.225mol
We know that 1 mole of any gas has
6.023 * 10²³ molecules.
Hence, number of molecules in Cl2
= 0.225mol * (6.023 * 10²³/mol)
= 1.35 * 10²³ molecules. (C)
In the Energy and Specific Heat lab, what temperature should be recorded as the final temperature of the water when measuring the food sample?
A. The temperature of the water when the food sample is first lit
B. The temperature of the water when the food sample has finished burning completely.
C. The highest temperature the water reaches as the sample burns
D. The temperature of the water after the food sample ash has been removed
Answer:
B. The temperature of the water when the food sample has finished burning completely.
Explanation:
Heat or thermal energy is a form of energy that transfers from one object to another due to a temperature difference between the objects. The units for heat are joules or calories.
Calorimetry is the measurement of heat energy released or absorbed in a chemical reaction. A calorimeter is used in calorimetry. The calorimeter operates on the Law of Conservation of Energy which states that energy is never created or destroyed but is transformed from one form to another or between objects.
In food calorimetry, the energy released when food is burned is measured by recording the rise in temperature of water in a calorimeter when a given mass of a food sample is burned completely.
Energy can be calculated using the formula: Q = mc ∆T
where Q = the energy in joules or calories, m = the mass in grams, c = specific heat and ∆T = the change in temperature (final temperature - initial temperature).
The temperature of the water when the food sample has finished burning completely is taken as the final temperature of the water. The sample is allowed to smolder for sometime before recording the final water temperature. This is because the water temperature will continue to rise after the flame has gone out.
3. What determines the frequency (color) of photons?
How many cells are a result of Meiosis?
Answer:
2
Explanation:
Cells divide and reproduce in two ways, mitosis and meiosis. Mitosis results in two identical daughter cells, whereas meiosis results in four sex cells.
A 6.40 g sample of a compound is burned to produce 8.37 g CO_2, 2.75 g H_2O, 1.06 g N_2, and 1.23 g SO_2. What is the empirical formula of the compound? Give your answer in the form C#H#N#O#S# where the number following the element’s symbol corresponds to the subscript in the formula. (Don’t include a 1 subscript explicitly).
The empirical formula :
C₁₀H₁₆N₄SO₇
Further explanationGiven
6.4 g sample
Required
The empirical formula
Solution
mass C :
= 12/44 x 8.37 g
= 2.28
mass H :
= 2/18 x 2.75 g
= 0.305
mass N = 1.06
mass S :
= 32/64 x 1.23
= 0.615
mass O = 6.4 - (2.28+0.305+1.06+0.615) = 2.14 g
Mol ratio :
= C : H : N : S : O
= 2.28/12 : 0.305/1 : 1.06/14 : 0.615/32 : 2.14/16
= 0.19 : 0.305 : 0.076 : 0.019 : 0.133 divided by 0.019
= 10 : 16 : 4 : 1 : 7
The empirical formula :
C₁₀H₁₆N₄SO₇
[10 pts]Iron and vanadium both have the BCC crystal structure and V forms a substitutional solid solution in Fe for concentrations up to approximately 20 wt.% V at room temperature. Determine the concentration in weight percent of V that must be added to iron to yield a unit cell edge length of 0.289 nm.
Answer:
The answer is below
Explanation:
The unit cell edge length (a) = 0.298 nm = 0.289 * 10⁻⁷ cm
The unit volume (V) = a³ = (0.289 * 10⁻⁷ cm)³ = 24 * 10⁻²⁴ cm³
There are 2 atoms per cell, hence N = 2. Also, [tex]n_a=avogadro\ constant=6.02*10^{23}\ mol^{-1}[/tex]
[tex]atomic\ weight\ of\ iron(A_f)=55.85,atomic\ weight\ of\ vanadium(A_V)=50.94,[/tex]
[tex]density\ of\ iron(\rho_f)=7.87,density\ of\ vanadium(\rho_v)=6.1.\\\\V=\frac{nA_{av}}{n_a\rho_{av}} \\\\A_{av}=\frac{100}{C_v/A_v+C_f/A_f} \\\\\rho_{av}=\frac{100}{C_v/\rho_v+C_f/\rho_f} \\\\C_v=concentration\ of\ vanadium,C_f=concentration\ of\ iron.\\\\V=\frac{nA_{av}}{n_a\rho_{av}}=\frac{n*\frac{100}{C_v/A_v+C_f/A_f}}{n_a*\frac{100}{C_v/\rho_v+C_f/\rho_f}}\\\\[/tex]
[tex]24*10^{-24}=\frac{2*\frac{100}{C_v/50.94+C_f/55.85}}{6.02*10^{23}*\frac{100}{C_v/6.1+C_f/7.87}}\\\\7.2=\frac{C_v/6.1+C_f/7.87}{C_v/50.94+C_f/55.85}\ \ \ (1) \\\\Also:\\\\C_v+C_f=100\%\ \ \ (2)\\\\\\solving\ equation\ 1\ and\ 2\ simultaneously\ gives:\\\\C_v=10\% \ and\ C_f=90\%\\\\[/tex]
identified the nucleus that is found in an item that has a stable valance electron configuration
Answer:
Nucleus 3 i believe
Calculate the mass of butane needed to produce 99.0 g of carbon dioxide.
Express your answer to three significant figures and include the appropriate units.
Answer:
32.7 g
Explanation:
Step 1: Write the balanced combustion reaction
C₄H₁₀ + 6.5 O₂ ⇒ 4 CO₂ + 5 H₂O
Step 2: Calculate the moles corresponding to 99.0 g of CO₂
The molar mass of CO₂ is 44.01 g/mol.
99.0 g × 1 mol/44.01 g = 2.25 mol
Step 3: Calculate the moles of C₄H₁₀ needed to produce 2.25 moles of CO₂
The molar ratio of C₄H₁₀ to CO₂ is 1:4. The moles of C₄H₁₀ needed are 1/4 × 2.25 mol = 0.563 mol.
Step 4: Calculate the mass corresponding to 0.563 moles of C₄H₁₀
The molar mass of C₄H₁₀ is 58.12 g/mol.
0.563 mol × 58.12 g/mol = 32.7 g
Bond length is the distance between the centers of two bonded atoms. On the potential energy curve, the bond length is the internuclear distance between the two atoms when the potential energy of the system reaches its lowest value. Consider that the atomic radius (sometimes called the covalent or bonding atomic radius) of an element is defined as one-half the distance between the bonded atoms in a homonuclear diatomic molecule. Actual bond lengths in molecules are determined experimentally by such methods as X-ray diffraction and microwave spectroscopy. However, these atomic radii values can be used to give an estimate of the upper limit of bond length in other (heteronuclear) molecules. Given that the atomic radii of H and Br are 37.0 pm and 115 pm , respectively, predict the upper limit of the bond length of the HBr molecule.
Answer:
152 pm
Explanation:
According to the question, we can estimate the bond length from the given values of the atomic radii. This now is the upper limit of the bond length for the molecule.
Since we have that;
Atomic radius of H= 37.0 pm
Atomic radius of Br = 115.0 pm
Bond length = Atomic radius of H + Atomic radius of Br
Bond length = 37.0 pm + 115.0 pm
Bond length = 152 pm
what are some sources of error associated with electroplating
Answer:
Cold Shuts. Cold shuts are one of the most common defects found in materials sent for electroplating.
Pitting
Sharp Edges
Cleavage Points
Unclean Manufacturing
Loss of Adhesion
Cracking After Plating — Hydrogen Cracking
Dull and Hazy Deposits in Plating.
Explanation:
a pressure of 10Nm -2 is equal to ?
Answer:
a pressure of 10 Nm -2 is equal to ?
1 atmosphere
Explanation:
A pressure of 10 N/m² is equal to 10 Pa and 9.86x10⁻⁵ atm.
Pressure (P) is the measure of the perpendicular force (F) applied to an object's surface area (A):
[tex] P = \frac{F}{A} [/tex]
Hence, the unit of the pressure is Newton per square meter (N/m²), which is defined as Pascal (Pa).
[tex] 1 Pa = 1 N/m^{2} [/tex]
Also, we have that 1 atm is equal to 101325 Pa, so:
[tex] P = 1 Pa*\frac{1 atm}{101325 Pa} =9.86 \cdot 10^{-6} atm [/tex]
So, in a pressure of 10 N/m² we have:
[tex] P = 10 N/m^{2} = 10 Pa = 9.86 \cdot 10^{-5} atm [/tex]
Therefore, a pressure of 10 N/m² is equal to 10 Pa and 9.86x10⁻⁵ atm.
You can find more about pressure here: https://brainly.com/question/8033367?referrer=searchResults
I hope it helps you!
Suppose two students grab an end of a rope. Both shake a rope once in a upward direction to create crests traveling at each other. What would you see when crests meet? What type of interference does this show?
Answer:
This creates destructive interference.
Explanation:
When the two ends meet they will cancel each other out.
Both students are shaking the rope in the upward direction. Hence their crest will meet up and form the constructive interference pattern. The intensity of the increases.
What is constructive interference ?When two waves moves in phase, their crest or troughs add up and the amplitude of the wave increases. This phenomenon is called constructive interference.
If the two waves are passing out of phase to each other then they undergo destructive interference. The amplitude of the destructive interference pattern reduces from their initial values.
Here, both students are shaking the rope in the upward direction. Thus, they are in moving in phase. Hence their crest will meet up and form the constructive interference pattern. The intensity of the increases.
Find more on interference?
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How many moles of hydrogen react with 4.5 moles of oxygen to synthesize water?
Answer:
9moles of hydrogen gas
Explanation:
To solve this problem, we write the reaction expression first;
2H₂ + O₂ → 2H₂O
We have been given the number of moles of oxygen gas to be:
Number of moles of oxygen gas = 4.5moles
From the balanced reaction expression:
1 mole of oxygen gas reacts with 2 moles of hydrogen gas
4.5moles of oxygen gas will react with 4.5 x 2 = 9moles of hydrogen gas
BALANCE THIS CHEMICAL EQUATION PLS, help:)
Answer:
4C₈H₄OH + 35O₂ → 32CO₂ + 10H₂O
Explanation:
The unbalanced reaction expression is given as:
C₈H₄OH + O₂ → CO₂ + H₂O
To solve this problem, we use a mathematical approach.
aC₈H₄OH + bO₂ → cCO₂ + dH₂O
Conserving C: 8a = c
H: 5a = 2d
O: a + 2b = 2c + d
Let a = 1, c = 8, d = [tex]\frac{5}{2}[/tex] , b = 35
4C₈H₄OH + 35O₂ → 32CO₂ + 10H₂O
100%
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Merriweath...
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6. What is the mass, in grams, of 1.92 moles of Ca(OH),?
Answer:
Mass = 142.25 g
Explanation:
Given data:
Mass of Ca(OH)₂ = ?
Number of moles of Ca(OH)₂ = 1.92 mol
Solution:
Formula:
Mass = number of moles × molar mass
Molar mass of Ca(OH)₂ = 74.09 g/mol
by putting values,
Mass = 1.92 mol × 74.09 g/mol
Mass = 142.25 g
which of these is an example of the climate of a region?
A. Dry
B. Foggy
C. Overcast
D. Sunny
its dry i think
Explanation:
it might be dry
Where and in what features is water found on Earth?
Answer: On Earth, liquid water exists on the surface in the form of oceans, lakes and rivers. It also exists below ground as groundwater, in wells and aquifers. Water vapor is most visible as clouds and fog. The frozen part of Earth's hydrosphere is made of ice: glaciers, ice caps and icebergs.
Which statement is always true about conversation of matter?
The mass of a system does not change during a chemical reaction
If a solid forms the mass of a system increases
If a gas forms the mass of a system decreases
The mass of a system changes when a substance changes from liquid to gas, but it does not change in a chemical reaction
Answer:
The mass of a system does not change during a chemical reaction
Explanation:
Correct Answers
Which of the following contains a polyatomic ion?
sodium iodide
carbon monoxide
Iron II oxide
ammonium chloride
Answer:
i think its oxide not too sure
Answer:
Its should be ammonium chloride.
A picture to help you with another question like this
What is the mass of 1.75 moles of Ca(H2C302)2?
Explanation:
first we have to find molar mass of ca(H2c3o2)2
40+(1*2)2+(12*3)2+(16*2)2
40+4+72+64=180g/mole
m=n*Mm
m=1.75mole*180g/mole
m=315g
What role do wolves play in the tundra?
Answer:
predator
Explanation:
Wolves, arctic foxes, and snowy owls are predators in the tundra.
Classify each as acidic or basic - pH 9 - pH 2.3 - pH 11 - pH 5 - solution where the concentration of hydronium ions [H ] is 0.0056 M - solution where the concentration of hydronium ions [H ] is 3.45 E-9 M.
Answer:
pH = 9: Basic; pH = 2.3: acidic; pH = 11: basic; pH = 5: Acidic; [H⁺] = 0.0056M: Acidic; [H⁺] = 3.45E-9M: Basic
Explanation:
A solution is defined as acidic when pH < 7 and as basic when pH > 7.
Also, pH = -log[H⁺].
Thus:
pH = 9: >7 → Basic
pH = 2.3: <7 → Acidic
pH = 11: >7 → Basic
pH = 5: <7 → Acidic
[H⁺] = 0.0056M, pH = -log0.0056M = 2.25: <7: Acidic
[H⁺] = 3.45E-9M, pH = 8.46: > 7: Basic
Which of the following BEST describes how these elements would be classified?
A.
Element Q is a nonmetal and element R is a nonmetal.
B.
Element Q is a metal and element R is a metalloid.
C.
Element Q is a nonmetal and element R is a noble gas.
D.
Element Q is a metal and element R is a noble gas.
A catalyst decreases the activation energy of a particular exothermic reaction by 56 kJ/mol, to 35 kJ/mol. Assuming that the mechanism has only one step, and that the products are 78 kJ lower in energy than the reactants, sketch approximate energy-level diagrams for the catalyzed and uncatalyzed reactions. What is the activation energy for the uncatalyzed reverse reaction
Answer:
Activation energy for the uncatalyzed reverse reaction = 103 kJ/mol
Explanation:
Activation energy decreases from = 56 kj/mol to 35 kj/mol
products = 78 KJ lower in energy than reactants
Activation energy for the uncatalyzed reverse reaction = 103 kJ/mol
attached below are the sketches of approximate energy-level for both catalyzed and uncatalyzed reactions
