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.
[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]
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 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
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
3. What determines the frequency (color) of photons?
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
The circuit below is powered by a 20-volt battery. What current is flowing through the on/off switch (when it is on, as shown)?
Answer:
The answer is "0.38 A".
Explanation:
Please find the missing image file in the attachment.
In the given image let:
[tex]R_{12} =R_1+R_2=16 \ \Omega \\\\R_{34} =R_3+R_4=20 \ \Omega \\[/tex]
[tex]R_P=\frac{R_{12} \cdot R_{34}}{R_{12} +R_{34}}[/tex]
[tex]= \frac{16 \cdot 20 }{16 +20}\\\\= \frac{320 }{36}\\\\= \frac{80 }{9}\\\\= 8.88 \ \Omega[/tex]
similarly,
[tex]R_{eq} =R_p+R_5+R_6\\\\[/tex]
[tex]=8.88+24+20\\\\=52.89 \ \Omega \\\\[/tex]
calculating the current value through a switch:
[tex]\to I=\frac{V}{R_{eq}} = \frac{20 \ v}{52.89 \Omega }=0.38\ A[/tex]
Answer:
D. 0.38 amperes
Explanation:
Got it correct on Gizmos
Gizmos explanation: This compound circuit contains two parallel branches connected in series to 2 more resistors. Each parallel branch contains 2 resistors in series. The resistance of the first branch is 5+11=16 ohms, and the resistance of the second branch is 20 ohms. Using the equivalent resistance formula, the resistance of this section is
1R=116+120=580+480=980
So R is 809, or 8.89 ohms. This is connected in series to a 24-ohm and a 20-ohm resistor, for a total resistance of 52.89 ohms. The battery voltage is 20 volts, so by Ohm's law
I=VR
I=2052.89=0.38amperes
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
ANSWER QUICK !!!
How many grams of hydrogen gas will be produced if you start with 15.0 grams of zinc and an excess amount of HCI?
balanced equation:
Zn + 2HCI = ZnCl2 + H2
Answer:
0.48g
Explanation:
Given parameters:
Mass of zinc = 15g
Unknown:
Mass of hydrogen gas = ?
Solution:
To solve this problem, we need to state the balanced reaction expression first;
Zn + 2HCl → ZnCl₂ + H₂
Find the number of moles of Zn;
Number of moles = [tex]\frac{mass}{molar mass}[/tex] = [tex]\frac{15}{63.4}[/tex] = 0.24mol
From the balanced reaction expression;
1 mole of Zn will produce 1 mole of H₂
0.24mole of Zn will produce 0.24mole of hydrogen gas
Mass of hydrogen gas = number of moles x molar mass
= 0.24 x (2 x 1)
= 0.48g
PLEASE HELP BRAINLIEST AND 15 points.
1. Which substance is nonvolatile ?
(1.5 Points)
Substance B, boiling point of 105 °C
Substance C, boiling point of 25 °C
Substance A, boiling point of 75 °C
Substance d, boiling point of 45 °C
Answer:
Substance B, boiling point of 105 °C
Explanation:
Non volatile substances have high boiling points
6.00 g of a certain Compound X, known to be made of carbon, hydrogen and perhaps oxygen, and to have a molecular molar mass of 26. g/mol, is burned completely in excess oxygen, and the mass of the products carefully measured:
product mass
carbon dioxide 20.31g
water 4.16 g
Use this information to find the molecular formula of X
Answer:
C2H2
Explanation:
Mass of Carbon in CO2[tex]= (12/44) (20.31)[/tex] grams [tex]= 5.54[/tex] gram
Mass of hydrogen in H2O [tex]= (2/18)(4.26)[/tex] grams [tex]= 0.46[/tex] gram
We will calculate the % of C and H in the sample
% C [tex]= (5.54/6) * 100 = 92[/tex]%
% H [tex]= (0.46/6)*100 = 7.7[/tex]%
Number of mole of C [tex]= 92/12 = 7.69[/tex]
Number of mole of H [tex]= 7.67/1 = 7.67[/tex]
Fractional share of C [tex]= 7.69/7.67 = 1[/tex]
Fractional share of H [tex]= 7.67/7.67 = 1[/tex]
Empirical Formula = CH
Empirical Mass [tex]= 12+1 = 13[/tex]
Molecular mass [tex]= 26[/tex]
Molecular Formula – CHn
N [tex]= 26/13 = 2[/tex]
Molecular Formula = C2H2
What role do wolves play in the tundra?
Answer:
predator
Explanation:
Wolves, arctic foxes, and snowy owls are predators in the tundra.
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
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)
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?
https://brainly.com/question/16098226
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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.
Set Grouper to 70%. How do you think this level of fishing will affect the populations of the other fish in the simulated reef? Explain your reasoning.
Answer:
Greatly affect.
Explanation:
This level of fishing will greatly affect the populations of the other fish in the simulated reef because overfishing disturbs the equilibrium in the marine ecosystem. One fish is a food of another fish or the big fish act as a controller which controls the population of other small fishes and in that way the ecosystem is present in equilibrium state so overfishing will greatly affect the marine ecosystem.
Which rule states that cracks on glass tend to form at a certain angle on the opposite side of the polnt of Impact?
The
rule states that cracks tend to form at a (n)
angle on the opposite side from the point of Impact.
Answer:
The 3R rule states that cracks tend to form at a (n) right angle on the opposite side from the point of impact.
Explanation:
which would be a stronger acid H3PO4 or H3PO2
Answer:
h3po2
Explanation:
Answer:
i think it is H3PO4
Explanation:
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
Ammonium phosphate is an important ingredient in many solid fertilizers. it can be made by reacting aqueous phosphoric acid with liquid ammonia. calculate the moles of ammonium phosphate produced by the reaction of 0.085 mol of ammonia. be sure your answer has a unit symbol, if necessary, and round it to the correct number of significant digits.
Answer:
0.028 mole of ammonium phosphate, (NH₄)₃PO₄.
Explanation:
We'll begin by writing the balanced equation for the reaction. This is illustrated below:
H₃PO₄ + 3NH₃ —> (NH₄)₃PO₄
From the balanced equation above,
3 moles of NH₃ reacted to produce 1 mole of (NH₄)₃PO₄.
Finally, we shall determine the number of mole of (NH₄)₃PO₄ produced by the reaction of 0.085 mole of ammonia, NH₃. This can be obtained as follow:
From the balanced equation above,
3 moles of NH₃ reacted to produce 1 mole of (NH₄)₃PO₄.
Therefore, 0.085 mole of NH₃ will react to produce = (0.085 × 1)/3 = 0.028 mole of (NH₄)₃PO₄.
Thus, 0.028 mole of ammonium phosphate, (NH₄)₃PO₄ were obtained from the reaction.
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
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
helpppp nowwww plssss!!!
Answer: B
Explanation:
an unknown substance has a mass of 57.4 g and occupies a volume of 34.3 ml. what is the density in g/ml?
Answer: 1.67
D=M/V
(D=57.4/34.3)= 1.67
100 POINTS FOR BEST ANSWER! What is the difference between LDOF and SDOF
An SDOF system is one whose motion is governed by a single, second-order differential equation. Only two variables, position and velocity are needed to describe the trajectory of the system. Many structures can be idealized as single degree-of-freedom systems.
The LDAP Data Interchange Format is a standard plain text data interchange format for representing LDAP directory content and update requests. LDIF conveys directory content as a set of records, one record for each object.
PLS HELLPPPP
Which of the following objects would have the greatest gravitational attraction between them if they were set 3.0 km apart?
A .20kg object and a 200kg object
A 10kg object and a 100kg object
A 30kg object and a 200,000kg object
A 400,000 kg object and a 100,000,000kg object
Answer:
A 400,000 kg object and a 100,000,000kg object
Explanation:
The objects with the most mass between them will have the greatest gravitational attraction.
This is why the last option is the right choice.
The reason for this is based on the Newton's law of universal gravitation which states that:
"the gravitational force of attraction between two bodies is directly proportional to the product of their masses and inversely proportional to the square of the distance between them".
So, the more the mass, the greater the gravitational attraction between two bodies.
The balanced equation for the production of sugars by photosynthesis is shown below.
This equation demonstrates the law of conservation of mass because
A.
there are more oxygen atoms on the right side of the equation than on the left.
B.
there is the same number of compounds on the right side of the equation as the left.
C.
there is the same number of each type of atom on the right side of the equation as the left.
D.
the sugar molecule on the right has the same mass as the carbon dioxide molecules on the left.
Answer:
Black
Explanation:
Answer:
the answer is
-there is the same number of each type of atom on the right side of the equation as the left.
Explanation:
i have study island too :')
WORTH 40 POINTS HELLPPPP
What class of element is Astatine (At)?
Answer:
halogen.
nonmetal.
Explanation:
GRADE 5 SCIENCE MYA-2020-2021
Testosters are testing the choict of light on a radiometer Team 1 finds that blue light makes the radiometer spin slower when a blue light is 35 centimeters (cm) away. To validate Team 1's test results, how must
Text with and that is 20 cm away
Test what that is 45 cm away
Test with a green light that is 40 cm away
Test with the light that is 35 cm away
Answer:
Test it with a blue light that is 45 cm away.
Explanation:
