Answer:
pH
7.0 = neutral.
(7–14) = basic
(0–6) = acidic
Explanation:
What are chemical changes of matter?
Answer:
Chemical Changes are also called Chemical Reactions. Chemical reactions involve combining different substances. The chemical reaction produces a new substance with new and different physical and chemical properties. Matter is never destroyed or created in chemical reactions.
Explanation:
What is the total energy change for the following reaction:CO+H2O-CO2+H2
Answer:
[tex]\large \boxed{\text{-41.2 kJ/mol}}[/tex]
Explanation:
Balanced equation: CO(g) + H₂O(g) ⟶ CO₂(g) + H₂(g)
We can calculate the enthalpy change of a reaction by using the enthalpies of formation of reactants and products
[tex]\Delta_{\text{rxn}}H^{\circ} = \sum \left( \Delta_{\text{f}} H^{\circ} \text{products}\right) - \sum \left (\Delta_{\text{f}}H^{\circ} \text{reactants} \right)[/tex]
(a) Enthalpies of formation of reactants and products
[tex]\begin{array}{cc}\textbf{Substance} & \textbf{$\Delta_{\text{f}}$H/(kJ/mol}) \\\text{CO(g)} & -110.5 \\\text{H$_{2}$O} & -241.8\\\text{CO$_{2}$(g)} & -393.5 \\\text{H$_{2}$(g)} & 0 \\\end{array}[/tex]
(b) Total enthalpies of reactants and products
[tex]\begin{array}{ccr}\textbf{Substance} & \textbf{Contribution)/(kJ/mol})&\textbf{Sum} \\\text{CO(g)} & -110.5& -110.5 \\\text{H$_{2}$O(g)} &-241.8& -241.8\\\textbf{Total}&\textbf{for reactants} &\mathbf{ -352.3}\\&&\\\text{CO}_{2}(g) & -393.5&-393.5 \\\text{H}_{2} & 0 & 0\\\textbf{Total}&\textbf{for products} & \mathbf{-393.5}\end{array}[/tex]
(c) Enthalpy of reaction [tex]\Delta_{\text{rxn}}H^{\circ} = \sum \left( \Delta_{\text{f}} H^{\circ} \text{products}\right) - \sum \left (\Delta_{\text{f}}H^{\circ} \text{reactants} \right)= \text{-393.5 kJ/mol - (-352.3 kJ/mol}\\= \text{-393.5 kJ/mol + 352.3 kJ/mol} = \textbf{-41.2 kJ/mol}\\ \text{The total enthalpy change is $\large \boxed{\textbf{-41.2 kJ/mol}}$}[/tex]
The activation energy (E*) for 2N2O ---> 2N2 + O2 is 250 KJ. If the k for this reaction is 0.380/M at 1001oK, what will k be at 298oK? What will the half-life be at both temperatures?
Answer:
Explanation:
GIven that:
The activation energy = 250 kJ
k₁ = 0.380 /M
k₂ = ???
Initial temperature [tex]T_1 =[/tex] 1001 K
Final temperature [tex]T_2 =[/tex] 298 K
Applying the equation of Arrhenius theory.
[tex]In \dfrac{k_2}{k_1 }= \dfrac{Ea}{R}( \dfrac{1}{T_1 }- \dfrac{1}{T_2})[/tex]
where ;
R gas constant = 8.314 J/K/mol
[tex]In \dfrac{k_2}{0.380 }= \dfrac{250 * 10^3}{8,314}( \dfrac{1}{1001 }- \dfrac{1}{298})[/tex]
[tex]In \dfrac{k_2}{0.380 }= -70.8655[/tex]
[tex]\dfrac{k_2}{0.380 }= e^{-70.8655}[/tex]
[tex]\dfrac{k_2}{0.380 }= 1.67303256 \times 10^{-31}[/tex]
[tex]{k_2}= 1.67303256 \times 10^{-31} \times {0.380 }[/tex]
[tex]{k_2}= 6.3575 \times 10^{-32}[/tex] /M .sec
Half life:
At 1001 K.
[tex]t_{1/2} = \dfrac{In_2}{k_1}[/tex]
[tex]t_{1/2} = \dfrac{0.693}{0.38}[/tex]
[tex]t_{1/2} =[/tex] 1.82368 secc
At 298 K:
[tex]t_{1/2} = \dfrac{0.693}{6.3575 \times 10^{-32}}[/tex]
[tex]t_{1/2} =1.09 \times 10^{31} \ sec[/tex]
What indicates how much of each reactant will be used up in a reaction?
A. The total moles of product
B. The molar mass of each element
C. The masses of final product
D. The coefficients of a balanced reaction
Answer:
D. The coefficients of a balanced reaction
Explanation:
Just took an a pex quiz
(I picked C and got it incorrect)
The coefficients of a balanced reaction. Hence, option D is correct.
What is a balanced equation?A balanced equation is a chemical reaction in which the number of atoms for each element in the reaction and oxidation numbers are the same for both the reactants and the products.
To adjust the substance condition, you need to ensure the number of molecules of every component on the reactant side is equivalent to the number of particles of every component on the item side.
To make the two sides equal, we need to duplicate the number of particles in every component until the two sides are equivalent.
Hence, option D is correct.
Learn more about balanced equations here:
https://brainly.com/question/7181548
#SPJ5
What shape is represented by three bound groups and one lone pair around a
central atom?
A. Bent
B. Tetrahedral
C. Linear
D. Trigonal pyramidal
Answer:
D Trigonal pyramidal
Explanation went over in class:
Answer:
D. Trigonal pyramidal
Explanation:
A P E X !
How many atoms are in 10g of Al
Answer:
The correct answer is
Explanation:
hope this helps u!!
which one of the following electronic configuration represents the element that forms simple ion with a charge of-3? (a)1s^2,2s^2,2p^6,3s^2,3p^1 (b)1s^2,2s^2,2p^6,3s^2,3p^3 (c)1s^2,2s^2,2p^6,3s^2,3p^6,3d^1,4s^2 (d)1s^2,2s^2,2p^6,3s^2,3p^6
Answer:
(b)
Explanation:
The 3s^2, 3p^6 orbitals form -3 charge.
This is the element phosphorous and an example of a -3 ion is in aluminium phosphide, AlP3.
The electronic configuration which represents the element forming a simple ion having with a charge of -3 is; 1s², 2s², 2p⁶, 3s², 3p³. Option B is correct.
In this electronic configuration, the element has a total of 16 electrons. To form a simple ion with a charge of -3, the element needs to gain three electrons. This is achieved by adding three extra electrons to the existing configuration.
When the element gains three electrons, the electron configuration becomes:
1s², 2s², 2p⁶, 3s², 3p⁶
This configuration represents the stable octet configuration, where the element has a complete outer shell with eight electrons. Since the charge is -3, it means the element has gained three extra electrons to achieve a stable configuration.
Therefore, the correct electronic configuration representing the element that forms a simple ion with a charge of -3 is 1s², 2s², 2p⁶, 3s², 3p³
Hence, B. is the correct option.
To know more about electronic configuration here
https://brainly.com/question/29184975
#SPJ2
A platinum resistance thermometer has resistances of 160.0 when placed in a 0°C ice bath and 243.8 when immersed in a crucible containing a melting substance. What is the melting point of this substance? (Hint: First determine the resistance of the platinum resistance thermometer at room temperature, 20°C.)
Answer:
the melting point T = 125.36°C
Explanation:
Given that:
The resistance of a platinum thermometer at 0°C is [tex]R_o[/tex] = 160.0 ohms
The resistance of a platinum thermometer when immersed in a crucible containing a melting substance [tex]R_t[/tex] = 243.8 ohms
The temperature coefficient at room temperature 20°C = ∝ = 0.00392
The objective is to determine the melting point of this substance
To do that ; at 20°C, the resistance of the platinum thermometer can be calculated as follows:
[tex]R_{20} = R_o(1 + \alpha \Delta T)[/tex]
[tex]R_{20} = 160(1 + (0.00392 \times (20-0)^0C))[/tex]
[tex]R_{20} = 160(1 + (0.00392 \times (20))[/tex]
[tex]R_{20} = 160(1 + (0.0784)[/tex]
[tex]R_{20} = 160(1.0784)[/tex]
[tex]R_{20} = 172.544 \ ohms[/tex]
The resistance of the platinum thermometer at t°C , [tex]R_t[/tex] = [tex]R_{20}(1 + \alpha \Delta T)[/tex]
[tex]243.8 = 172.544(1 + 0.00392 \times (T-20)^0C}[/tex]
[tex]\dfrac{243.8}{ 172.544 }= (1 + 0.00392 \times (T-20)^0C}[/tex]
[tex]1.413 = (1 + 0.00392 \times (T-20)^0C}[/tex]
[tex]1.413-1 = 0.00392 \times (T-20)^0C}[/tex]
[tex]0.413 = 0.00392 \times (T-20)^0C}[/tex]
[tex]\dfrac{0.413 }{0.00392} = (T-20)^0C}[/tex]
105.36°C = (T - 20) °C
T = 105.36°C + 20 °C
T = 125.36°C
As defined by Aristotle, which one of the following is an element?
1. water 2. air 3. soil 4. none of them
Answer:
4
Explanation:
none of them
they are compounds and mixtures
Answer:
4. none of them
Explanation:
Water is a compound.
Air is a mixture.
Soil is a mixture.
None of them are elements.
what is the difference between the atom and isotope
Answer:
Atoms consist of a nucleus made of protons and neutrons orbited by electrons.
Isotopes are atoms that have same number of protons but they differ in the number of neutrons and in atomic mass.
Answer:
Isotopes are atoms that have the same numbers of protons but different numbers of neutrons. An ion is an atom that has gained or lost electrons, so it now has more or fewer electrons than it does protons. So an ion has a negative or positive charge.
Hope it helps :)
List four examples of diffusion seen in daily life.
Answer:
Spraying perfume in one corner of the room and the smell travels to the other side of the room
Explanation:
Escribe verdad o falso: La clorofila capta la energía luminosa del sol. () La fotosíntesis degrada las sustancias orgánicas que nesecitas las células()
Answer:
La clorofila capta la energía luminosa del sol. (verdadero) La fotosíntesis degrada las sustancias orgánicas que nesecitas las células(falso)
Explanation:
La clorofila es la encargada de dar el pigmento de color verde en las plantas y la que transforma la energia luminica en energia quimica, es por eso que es verdadera.
La fotosintesis NO degrada las sustancias organicas, sino que transforma un sustrato inorganico en una fuente energetica organica para las plantas.
Esto se debe por que las plantas o vegetales son autonomas, es decir que se autoabastecen energeticamente sin necesidad de ingerir alimentos como en el caso de los mamiferos.
Select the correct answer.
Which of these conditions would most likely cause a decrease in the population of any species?
ОА.
increased competition for resources
improved access to mates
OC.
elimination of predators
OD
decrease in pathogens
Answer(A increased competition for resources
Hope you get it right have a nice day
Answer:
A. increased competition for resources
Explanation:
PLEASE HELP A woman travels to Canada where milk is sold in liters. She wants to buy enough milk at the grocery store to last 5 days and she knows at home she uses 0.75 gallons per week. How many liters must she buy?
Answer:
About 2 liters
Explanation:
Since 1 gallon equals 3.785 liters, you figure out how many liters per week she uses by 3.785 x 0.75 which is 2.83875. Then divide that by 7 which is 0.405535 liters per day. Then multiply that by 5 days which is 2.027 liters in 5 days.
Which of the following is the best explanation for why it is important to follow lab safety guidelines
a. Following laboratory safety guidelines prevents all lab accidents.
b. Following laboratory safety guidelines minimizes the chance of lab ac
C. Following laboratory safety guidelines prevents fires.
d. Following laboratory safety guidelines allows quick response during la
Please select the best answer from the choices provided
Answer:
B
Explanation:
The main aim of lab rules is to minimize the no of accidents
Based on the information that is given, which atom in the table has the highest mass?
The question is incomplete, the complete question is;
Atom Number of protons Number of electrons Number of neutrons
1 39 39 52
2 40 40 50
3 39 39 54
4 40 40 51
Based on the information that is given, which atom in the table has the highest mass?
a. 1
b. 2
c. 3
d. 4
Answer:
c
Explanation:
The relative atomic mass is given as; number of protons + number of neutrons. If we take the relative atomic mass of each of the options;
1) 39 +52 = 91
2) 40+50 = 90
3) 39 + 54 = 93
4) 40 + 51 = 91
Thus 3 has the highest mass as seen above, hence the answer given.
Which Group has different numbers of valence electrons?
A. Alkaline earth metals
B. Alkali metals
C. Transition metals
D. Halogens
Answer:
[tex]c. \: transition \: metals[/tex]Transition metals (Group C) have different numbers of valence electrons compared to the other groups mentioned. Therefore option C is correct.
Transition metals (Group 3-12) have varying numbers of valence electrons. This is because their valence electrons are located in more than one energy level or subshell.
The number of valence electrons for transition metals can range from 1 to 12, depending on the specific element within the group. The varying numbers of valence electrons in transition metals contribute to their diverse chemical properties and ability to form multiple oxidation states.
Therefore, transition metals (Group C) have different numbers of valence electrons compared to the other groups mentioned.
Know more about transition metals:
https://brainly.com/question/29828769
#SPJ2
Molar mass of Al(OH)3 =
Answer:
78.01 g/mol
Explanation:
To find the molar mass of Al(OH)₃, we have to look at the mass of each individual element on the periodic table.
Al - 26.98
O - 3(16.00) = 48.00
H - 3(1.01) = 3.03
Now add it all together.
26.98 + 48.00 + 3.03 = 78.01 or 78 g/mol
Hope that helps.
What percentage of the total incoming radiation to the Earth reaches the ground? 20 30 40 70
Answer: 22.5 percent of incoming solar radiation goes directly to the surface of the Earth and is absorbed.
Explanation: Transfer of radiation through a planet's atmosphere. A planet and its atmosphere, in our solar system, can radiate back to space only as much energy as it absorbs from incoming solar radiation.
Answer:
Explanation:
I have the notes
"Only about 40 percent actually reaches the surface of the earth"
"our atmosphere and clouds reflect bout 40 percent of incoming solar radiation back into outer space"
"The remaining 60 percent is responsible for warming the earth"
"About 20 percent of this radiation is absorbed directly by the atmosphere"
Calculate mole fraction of ethylene
Glycol in solution
containing 20% g C2H6O2 by mass.
Answer:
Explanation:
20% of C2H6O2
since its a solution, this means that it has 20g of ethylene glycol and the rest is water.
Molar mass of C2H6O2 = (12 x 2) + (1 x 6) + (2 x 16)
= 62
mole = mass/molar mass
Moles of C2H6O2 = 20/62
= 0.322 mol
Moles of water = 80/18
= 4.444 mol
mole fraction = mol of solute / tatal mol of solution
Mole fraction of ethylene glycol = 0.322/(0.322 + 4.444)
= 0.068
Mole fraction of water = 1 - 0.068
= 0.932
Help me pls!
What is heliuim?
Answer:
it's a chemical Element
Explanation:
symbol He
atomic number 2.
When the name of ions end with ide, is it true that they are all negative ions
A reaction is in equilibrium as shown: A + B C + D. Calculate the equilibrium constant in the final concentrations stabilized at: A= 9.6 M B= 10.0 M C= 4.0 M D= 4.0 M K =
Answer:
K = 0.167
Explanation:
The equilibrium constant, K of a reaction, is defined as the ratio of the concentrations of products and concentrations of reactants.
For the reactions:
A + B ⇄ C + D
For the definition, K is:
K = [C] [D] / [A] [B]
K = [4.0M] [4.0M] / [9.6M] [10.0M]
K = 0.167why the filament of bulb has high melting point
Answer:
The filament of a bulb has a high melting point because of the heat generated inside the bulb.
Explanation:
When electricity is concentrating and run through a bulb, it starts to generate heat. Leave it on long enough and it will start to build up a lot of heat. Have you ever tried touching a light bulb when it has been all day? It's scorching to the skin.
Since electricity generates heat, the bulb's filament has to have a high melting point so it doesn't melt, destroy the bulb, and leave you light-less. If the filament has a high melting point, then it is able to withstand heat generated by electricity and provide you light.
Select all the correct answers.
What does an increase in the temperature of air indicate?
Answer:
a.the air has less thermal energy so that the temperature increases
An object starts at position 12 on a horizontal line with a reference point of O. What is the position of the object if it
moves 14 units to the left?
O-26
O-2
O 2
O 26
Answer:
O-2
Explanation:
We assume your reference point is 12 units to the left of the position designated as 12. Then 14 unit to the left will be 2 units left of O, or O-2.
An object starts at position 12 on a horizontal line with a reference point of 0. What is the position of the object if it moves 14 units to the left?
THE ANSWER IS -2
What's the valency of sulphur for NaHSO4 and why?
Explanation:
According to the periodic table, it has 6 valance electrons in its outermost shell of an atom. so, the valancy must be 2.
we usually subtract the valancy from 8 to no. of electrons if no. of electrons in its outermost shell is more than 5.
so, 8-6=2
is the valancy of sulpher here.
what is the valency of hydroxide
Answer:
Its valancy is 1.
As it has the formula OH-.
It has valancy 1.
hope it helps..
a 2.000-g sample of a hydrated copper sulfate is heated and the waters of hydration are removed if that mass of the remaining salt is 1.278 g what was the percentage of water in the original hydrate
Answer:
36.1%
Explanation:
The following data were obtained from the question:
Mass of hydrated copper sulfate = 2 g
Mass of anhydrous copper sulfate = 1.278 g
Percentage of water =..?
Next, we shall determine the mass of water in the hydrated copper sulfate.
This can be obtained as follow:
Mass of hydrated copper sulfate = 2 g
Mass of anhydrous copper sulfate = 1.278 g
Mass of water =...?
Mass of water = Mass of hydrated copper sulfate – Mass of anhydrous copper sulfate
Mass of water = 2 – 1.278
Mass of water = 0.722 g
Finally, we can obtain the percentage of water in the hydrated copper sulfate as follow:
Mass of water = 0.722 g
Mass of hydrated copper sulfate = 2 g
Percentage of water =..?
Percentage of water = mass of water /mass of hydrate x 100
Percentage of water = 0.722/2 x 100
Percentage of water = 36.1%
Therefore, the percentage of water in the hydrated copper sulfate is 36.1%
Define the term “Tyndall effect”. Which of the following would show Tyndall effect:- (Starch solution, sodium chloride solution, alcohol and water mixture)
Answer:
Tyndall Effect is the phenomenon of scattering of light by particles in a colloid or in a very fine suspension.
Starch solution would show Tyndall effect.
N/B: Heterogeneous mixtures show Tyndall effect.
Answer:The Tyndall effect is light scattering by particles in a colloid or in a very fine suspension. Also known as Willis–Tyndall scattering, it is similar to Rayleigh scattering, in that the intensity of the scattered light is inversely proportional to the fourth power of the wavelength, so blue light is scattered much more strongly than red light. An example in everyday life is the blue colour sometimes seen in the smoke emitted by motorcycles, in particular two-stroke machines where the burnt engine oil provides these particles.
Under the Tyndall effect, the longer wavelengths are more transmitted while the shorter wavelengths are more diffusely reflected via scattering. The Tyndall effect is seen when light-scattering particulate matter is dispersed in an otherwise light-transmitting medium, when the diameter of an individual particle is the range of roughly between 40 and 900 nm, i.e. somewhat below or near the wavelengths of visible light (400–750 nm).
It is particularly applicable to colloidal mixtures and fine suspensions; for example, the Tyndall effect is used in nephelometers to determine the size and density of particles in aerosols and other colloidal matter (see ultramicroscope and turbidimeter).
It is named after the 19th-century physicist John Tyndall.
Explanation: