Answer:
45 °C.
Explanation:
From the question given above, the following data were obtained:
Heat (Q) = 1125 J
Mass (M) = 250 g
Final temperature (T₂) = 55 °C
Specific heat capacity (C) = 0.45 J/gºC
Initial temperature (T₁) =?
The initial temperature of the iron can be obtained as illustrated below:
Q = MC(T₂ – T₁)
1125 = 250 × 0.45 (55 – T₁)
1125 = 112.5 (55 – T₁)
Divide both side by 112.5
1125/112.5 = 55 – T₁
10 = 55 – T₁
Collect like terms
10 – 55 = –T₁
–45 = –T₁
Multiply through by –1
45 = T₁
T₁ = 45 °C
Therefore, the initial temperature of the iron is 45 °C
PLZ PLZ PLZ PLZ PLZ PLZ PLZ PLZ PLZ PLZ PLZ PLZ PLZ PLZ HELP ME......
Answer:
a) clockwise
b) clockwise and
c) anticlockwise
2. A photon of wavelength for 4 x10 -7 m strikes on the metal surface the work
function of the metal being 2.13 eV.Calculate (i)the energy of the photon in
eV(ii) the kinetic energy of the emission(iii) velocity of the photoelectron
[1ev=1.602x10-19 J]
Answer:
See explanation
Explanation:
Energy of the photon;
E = hc/λ
h= Planks constant
c= speed of light
λ = wavelength
E= 6.6 × 10^-34 × 3 × 10^8/4 x10 -7
E = 4.95 × 10^-19 J
If 1ev=1.602x10-19 J
x = 4.95 × 10^-19 J
x= 3.1 ev
From Einstein's photoelectric equation;
KE = E - Wo
Where;
KE = kinetic energy of ejected photoelectron
E= energy of the photon
Wo= work function of the metal
KE = 3.1 eV - 2.13 eV
KE= 0.97 eV
KE = 0.97 eV × 1.602x10-19 J
KE = 1.55 × 10^-19 J
KE = 1/2 mv^2
1.55 × 10^-19= 1/2 × 9.1 × 10^-31 × v^2
v= √2 × 1.55 × 10^-19/9.1 × 10^-31
v= 5.8 × 10^5 m/s
the element of group 1 are reactive but those of group 18 are inert, why
Answer:
Because elements of group 1 does not have stable electronic configuration and elements of group 18 have stable electronic configuration.
Explanation:
Because elements of group 1 do not contain stable electronic configuration and elements of group 18 include stable electronic configuration.
What are the element of group 1?Group 1 elements contain the alkali metals, Li, Na, K, Rb, Cs, and Fr. The alkali metals exist all soft, shiny, and metallic when cut. They react efficiently with water, have low melting points and densities, and are good conductors of electricity. They all include one valence electron that they lose easily to form ions. Noble gas exists as any of the seven chemical elements that create up Group 18 (VIIIa) of the periodic table. The elements exist as helium (He), neon (Ne), argon (Ar), krypton (Kr), xenon (Xe), radon (Rn), and oganesson (Og).
The element of group 1 exist as reactive but those of group 18 exist as inert Because elements of group 1 do not contain stable electronic configuration and elements of group 18 include stable electronic configuration.
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The density of water is 1 g/cm3. Brent used the following method to convert 1 g/cm3 to kg/m3. An equation is shown. The expression on the left has three terms separated by the multiplication sign. The first term is 1 g by 1 cubic cm. The second term is 1 kg by 1000 kg. The third term is 100 cm raised to the power of 3 divided by 1 m raised to the power of 3. The number on the right of the equal to sign is 1000 kg per cubic meter. (1 kg = 1,000 g and 1 m = 100 cm) What is the error in Brent's conversion method?
Answer:
The error includes;
a) The wrong denominator for the equivalent fraction of kilograms to grams
b) The use of the scale factor of length rather than the scale factor of volume for the equivalent fraction of cubic centimeters to cubic meters
c) The arrival at the correct 1000 kg/m³ rather than 0.1 g/m³ based on the expression on the left of the equation
Explanation:
The density of water = 1 g/cm³
The given equation is presented as follows;
1 g/cm³ × 1 kg/(1000 kg) × 100 cm³/(1 m³) = 1000 kg/m³
The error in the conversion method are;
a) The conversion, 1 kg/(1,000 kg) has an error, the correct conversion is (1 kg)/1,000 g)
b) The volume conversion error, 100 cm³/(1 m³), the correct volume conversion is (100 cm)³/(1 m³) = 1,000,000 cm³/(1 m³)
c) The right of the equal to sign error; using the left side expression only, the (wrong) answer is 0.1 g/m³
The correct equation is presented as follows;
1 g/cm³ × 1 kg/(1000 g) × 1,000,000 cm³/(1 m³) = 1000 kg/m³
Answer:
C. 1,000 kg should be written as 1,000 g.
Explanation:
Got it right on my test :)
Which factor would speed up a chemical reaction? (Choose all that apply)
Decreasing particle size
Increasing the temperature
Decreasing the temperature
Increasing particle size
Answer:
Increasing the temperature
Increasing particle size
Explanation:
Increasing the temperature allows for particles and molecules to move faster (because there is an increase in energy) and allows for more collisions.
∴ Increasing the temperature would be an answer.
Increasing the particle size allows for more surface area and a greater chance for particles to collide with each other.
∴ Increasing particle size would be an answer.
Topic: AP Chemistry
Unit: Kinetics
hii pls help me to balance the equation thanksss
Explanation:
2KCLO3 (s) = 2KCl (s) + 3O2 (g)
In the compound Ni2O3, nickel's oxidation number is_____
oxidation number is -2.
and oxygen's
Answer:
+3
Explanation:
The name of this compound would be nickel (III) oxide. Oxygen typically has a charge of -2. Given there are 3 oxygen atoms, that would equal a charge of -6. The nickel is the cation and must equal the charge of the anion, so must have a charge of +6. Since there are 2 nickel atoms, the charge on each must be +3.
Câu 6: Cho 4,2 gam este đơn chức no E tác dụng hết với dung dịch KOH ta thu được 4,76
gam muối natri. Vậy công thức cấu tạo của E có thể là:
At what approximate temperature and pressure can all three phases of water exist simultaneously?
0°C, 760 mmHg
0°C, 5 mmHg
80°C, 380 mmHg
100°C, 760 mmHg
Answer:
0⁰c , 5 mmHg
Explanation:
Because at this temperature we all know water can be in state of both solid and liquid and when pressure is decreased it can be in form of gas too
What is said to have happened to the electrons in an atom in its ground state absorbs a quantum of energy from light
Answer:
The electron from the ground state to occupy a next energy level. In this case,we say that the electron is excited
Name three metals on the periodic table and their uses
PLS HELP
Câu 1: Trong các dung dịch sau, dung dịch nào làm quỳ tím đổi màu xanh?
A. HCl B. H2SO4 C. NaOH D. NaCl
Câu 2: Bazơ nào dưới đây là bazơ không tan?
A. KOH B. NaOH C. Cu(OH)2 D. Ca(OH)2
Câu 3: Trong các chất sau đây, chất nào không phải là muối?
A. HCl B. KCl
C. NaOH
C. Cu (OH)
A. HCl
Please help with the Volume one
Answer:
im a just achild
Explanation:
Answer:
c
Explanation:
0.5dm³
follow me if you want
What is the pH value of lithium chloride?
Answer:
0.0003HERE IS YOUR ANSWERPropane can be cracked to produce propane and hydrogen. Complete the symbol equation for the reaction.
Answer:
Explanation:
C3H8= C3H6 +H2
list from soft to hard
List the following minerals in order from softest to hardest:
apatite, calcite, talc, quartz, diamond.
Convert the following moles to grams :)
1. 2.4 moles sulfur
2. 1.5 moles BeI2
3. 7.5 moles C6H12O6
Answer:
3
Explanation:
sky is high and I am good.
I need help with question 2
Answer:
here's the answer to your question
N2 H4 (1) + O2
N2 (a) + 2H20()
PLEASE HELP ASAP!
How many grams of hydrazine (N2Ha) are needed to produce 52,4 g
water?
a 31.0
O b
b. 186
c. 32.0
d. 46.5
Answer:
d. 46.5 g
Explanation:
First, you need to start with a properly balanced equation:
N₂H₄(l) + 3O₂(g) -> 2NO₂(g) + 2H₂O(l)
Then, find the moles of water produced:
2H = 2.01568 amu
O = 15.999 amu
________________
18.01468 amu
52.4 g ÷ 18.01468 amu = 2.9087 moles
The mole ratio in our balanced formula between N₂H₄ : H₂O is 1 : 2, so divide moles of H₂O by 2 to get moles of N₂H₄
2.9087 moles ÷ 2 = 1.45435 moles of N₂H₄
Then, calculate the atomic mass of N₂H₄:
2N = 28.0134 amu
4H = 4.03136 amu
________________
32.04476 amu
Finally, calculate the mass in grams of N₂H₄:
1.45435 moles • 32.04476 amu = 46.604 g
Question 10 of 10 A certain seed is surrounded by a sticky coating. It is fairly dense and does not float in water. How is this seed most likely spread?
A. It is dispersed by the wind, and it sprouts after it falls to the ground
B. It drops to the bottom of a body of water, where it sprouts.
C. It attaches to the fur of an animal, and it sprouts after it falls from the animal's fur.
D. Animals eat it, and it is deposited in their waste.
Type the correct answer in the box. Express your answer to two significant figures. You are performing a reaction with 1.7 moles of hydroiodic acid and 3.43 moles of zinc bromide: 2HI + ZnBr2 → 2HBr + ZnI2. How many moles of zinc iodide can be made? The theoretical yield is moles of zinc iodide.
Answer:
1.34 34343 he did
Explanation:
i did the test
Answer:
0.85
Explanation:
What is the energy of a photon that emits a light of
frequency 6.42 x 1014 Hz?
A. 4.67 x 10-19 J
B. 4.25 x 10-19
C. 3.10 x 10-19 J
D. 9.69 x 10-19 J
Answer:
Option B is correct [4.25 x 10-19J]
Explanation:
Book your exam with us for 100% result
4.78×[tex]10^{-19}[/tex] J is the energy of a photon that emits light of
frequency 6.42 x[tex]10^{14}[/tex] Hz.
What is the frequency?Frequency is the rate at which current changes direction per second. The energy of a single photon is given by:
E =hν
where
E is the energy
h is the Planck constant
f is the frequency of the light
The chemical equation for the energy of a photon is given by:
E =hν , where h is the Planck constant and ν is the frequency.
E =hν = 6.626×[tex]10^{-34}[/tex] Js × 7.21×[tex]10^ {14}[/tex]
[tex]s^{-1}[/tex] = 4.78 ×[tex]10^{-19}[/tex] J
Hence, 4.78×[tex]10^{-19}[/tex] J is the energy of a photon that emits light of
frequency 6.42 x[tex]10^{14}[/tex] Hz.
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0.2g of water represents how many mole?
Answer:
0.0111moles
Explanation:
as moles = mass/ mr(16+1+1)
so 0.2g / 18
gives you 0.111moles
hope this helps :)
Suggest a way that a scientist could create an even more accurate model of universe expansion
Answer:
Between galaxies, retake the measurement.
Explanation:
Among both galaxies, reiterate the measurements. Instead of utilising a balloon, a scientist might create a model that shows in which everything really is and how cosmos is expanding rather than expanding. By inflating up the atmosphere to 1/2, 3/4, and full size, continue the operation.
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Uranium-235 and uranium-238 are different ________ of uranium
(Apx answers please)
Answer:
Isotopes
Explanation:
An isotope are the atoms of an element with similar chemical identity and number of protons but different atomic masses. This means that isotopes of an element differ from one another by their number of NEUTRONS.
For example, the uranium element possesses isotopes as follows: Uranium-235 and uranium-238. This two isotopes have the same chemical identity and number of protons/atomic no., which is 92. However, the atomic masses (235 and 238) are different.
Answer:
Isotopes
Explanation:
4. what reaction fuels the burning of the sun? A.fission B.fusion C.combustion D.transmutation
Answer:
A
Explanation:
Answer:
fusion is what fuels the burning of the sun,it's the combining of light elements into heavier elements to produce energy.the sun produces a large amount of energy by combining very light elements with heavier elements.
I hope this helps
Please help I have been stuck on this problem for a couple hours and can't figure it out
Answer:
11.92 Liters O₂(g) at STP
Explanation:
For most stoichiometry problems, if one will convert all given data into moles, solve by rxn ratios, then finish by converting to needed dimensions to complete problem.
2Pb(NO₃)₂ => 2PbO + 4NO₂ + O₂
Given 237.5 grams PbO formed in reaction = 237.5 g/223.2 g/mole = 1.064 mole PbO
From equation ratios, moles O₂ formed = 1/2(moles PbO) = 1/2(1.064 moles O₂) = 0.532 mole O₂
0.532 mole O₂ = 0.532 mole x 22.4 liters/mole at STP = 11.91756272 liters (calculator answer) ≅ 11.92 liters O₂ at STP (4 sig.figs. based on given 237.5g PbO)
True or false, The universal gas constant, R, is . 0821 when we use mm Hg as our unit for pressure
Answer:
This is true.
Explanation:
R should be 0.0821
Good luck!
A chemist sets up a chemical reaction but finds that none of the reactant molecules have the required activation energy. What is the result?
A.
Products will form with less energy input.
B.
No products will be formed.
C.
The products will form too quickly.
D.
Products will convert to reactants.
Answer:
B.
No products will be formed.
