Answer:
5010J
Explanation:
The following data were obtained from the question:
Mass (m) = 15g
Heat of fusion (ΔHf) = 334J/g
Heat required (Q) =..?
The heat energy required to melt the ice can be obtained as follow:
Q = m·ΔHf
Q = 15 x 334
Q = 5010J
Therefore, the heat energy required to melt the ice is 5010J.
(c)
Suggest a reason why substance E does not conduct electricity in both solid and
molten states.
Answer:
Substance E does not conduct electricity in both solid and molten states because of very low melting and boiling points.
In both solid and molten state free electrons are required to conduct electricity. substance E has low boiling and melting point which means substance will have relatively weak bonds. Because of weak bonds substance E might not have much free electron in its outermost shell that can cause the electric current by their coordinated movement.
Hence, substance E is unable to conduct in both melting and molten state.
Who was the second person to organize the elements on the periodic table and what property did he use to re-organize them?
Answer:
Dmitri Mendeleev
Explanation:
He was a Russian Scientist who decided to reorganize the periodic table after other notable scientists such as Antoine-Laurent Lavoisier had also tried to organize it based on the states of matter of the elements.
Mendeleev reorganized the period in the order of increasing atomic mass although there were some other modifications by modern scientists.
Please can someone help I will mark brainiest!
Answer:
2Cl- ⇒ Cl ↓2+ 2e
Explanation: sorry if this is not what you were looking for.
The ____ contains the highest concentration of ozone. (troposphere (exosphere ( stratosphere ( mesosphere
Answer:
the answer is stratosphere.
about 90% of ozone is found in the stratosphere.
The reaction 2 NO(g) ⇌ N2(g) + O2(g) has a value of Keq = 2400 at a temperature of 2000 K. If 0.570 mol of NO(g) is initially placed in a 3.0 L container, calculate the equilibrium concentrations of each gas
Answer:
[tex][N_2]_{eq}=0.094M[/tex]
[tex][O_2]_{eq}=0.094M[/tex]
[tex][NO]_{eq}=0.002M[/tex]
Explanation:
Hello,
In this case, for the given chemical reaction, we write the following law of mass action:
[tex]Keq=\frac{[N_2][O_2]}{[NO]^2}[/tex]
That in terms of the change [tex]x[/tex] due to the reaction extent (ICE procedure) we can write:
[tex]Keq=\frac{x*x}{([NO]_0-2x)^2}[/tex]
Thus, the initial concentration of nitrogen monoxide is:
[tex][NO]_0=\frac{0.570mol}{3.0L} =0.19M[/tex]
Thereby, we write:
[tex]2400=\frac{x*x}{(0.19-2x)^2}[/tex]
That we can solve by suing the quadratic equation formula or solver to obtain two roots:
[tex]x_1=0.094M\\x_2=0.096M[/tex]
Nevertheless, the correct answer is 0.094 M since the other root will produce a negative concentration of nitrogen monoxide at equilibrium, therefore, the equilibrium concentrations turn out:
[tex][N_2]_{eq}=x=0.094M[/tex]
[tex][O_2]_{eq}=x=0.094M[/tex]
[tex][NO]_{eq}=0.19M-2x=0.19M-2(0.094M)=0.002M[/tex]
Best regards.
I NEED HELP PLEASE, THANKS! :)
The density of water at 4.00°C is 0.967 g/mL. How many molecules of water are present in a 499.8 mL bottle of water? Express your answer to the correct number of significant figures.
Answer:
[tex]\large \boxed{1.615 \times 10^{25}\text{ molecules water}}[/tex]
Explanation:
You must calculate the mass of the water, convert it to moles, and then calculate the number of molecules.
1. Mass of water
[tex]\text{Mass } = \text{499.8 mL} \times \dfrac{\text{0.967 g}}{\text{1 mL}} = \text{483.3 g}[/tex]
2. Moles of water
[tex]\text{Moles of water} = \text{483.3 g water} \times \dfrac{\text{1 mol water}}{\text{18.02 g water}} = \text{26.82 mol water}[/tex]
3. Molecules of water
[tex]\text{No. of molecules} = \text{26.82 mol water} \times \dfrac{6.022 \times 10^{23}\text{ molecules water}}{\text{1 mol water}}\\\\= \mathbf{1.615 \times 10^{25}}\textbf{ molecules water}\\\text{The sample contains $\large \boxed{\mathbf{1.615 \times 10^{25}}\textbf{ molecules water}}$}[/tex]
The number of molecules of water present in the bottle is 1.62×10²⁵ molecules.
We'll begin by calculating the mass of the water in the bottle.
Density of water = 0.967 g/mLVolume of water = 499.8 mLMass of water =?Mass = Density × Volume
Mass of water = 0.967 × 499.8
Mass of water = 483.3066 g
Finally, we shall determine number of molecules of water in the bottle.
From Avogadro's hypothesis,
1 mole of water = 6.02×10²³ molecules
But,
1 mole of water = 18 g
Thus, we can say that:
18 g of water = 6.02×10²³ molecules
Therefore,
483.3066 g of water = (483.3066 × 6.02×10²³) / 18
483.3066 g of water = 1.62×10²⁵ molecules
Thus, the number of molecules of water in the bottle is 1.62×10²⁵ molecules.
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A simple experiment to demonstrate that NaOH is a stronger alkali than NH3
Answer:
pH value test can be used to demonstrate that NaOH is a stronger alkali than NH3
Explanation:
pH value test can be used to demonstrate that NaOH is a stronger alkali than NH3. This is done by measuring the same volume of equal concentration of hydroxide and ammonia. A glass rod was dipped into 0.2 M of sodium hydroxide and 0.2 M of ammonia, each drop of solution was then placed on a pH paper matched with a color chart and the pH value was recorded.
The result showed that sodium hydroxide being a strong alkali would dissociate completely in aqueous solution thereby having a higher pH while ammonia would dissociate slightly/partially in aqueous solution thereby having a lower pH value
Why does the presence of lone pairs contribute to the polarity of a water molecule
Explanation:
They allow the bonds between oxygen and hydrogen to be single. They increase the partial positive charge on the oxygen atom. They counter the uneven pull on electrons between the atoms.
And ironic bonds what happens to electrons? No
Answer:
metals donate electrons to nonsmetals
Twenty liters of NO gas react with excess oxygen. How many liters of NO2 gas are produced if the NO gas reacts completely?
Answer:
2O L
Explanation:
The balanced chemical equation is 2NO+O
2
→2NO
2
Thus, 2 moles of NO will produce 2 moles of NO
2
.
Also, the volume is directly proportional to the number of moles.
Therefore, 20 L of NO will produce 20×
2
2
=20 L of NO
2
Select True or False: Nitric acid is formed by the gas-phase hydrolysis of N2O5. The energy profile curve for the reaction N2O5 H2O → 2HNO3 is shown here. The reaction is endothermic and the activation energy of the reverse reaction is larger than for the forward reaction.
Answer:
True
Explanation:
Because Nitric acid is formed by the gas-phase hydrolysis of N2O5. The energy profile curve for the reaction N2O5 H2O → 2HNO3 is shown here. The reaction is endothermic and the activation energy of the reverse reaction is larger than for the forward reaction.
Match these people to the discoveries or work that they are known for. Galileo developed geocentric theory Aristotle developed heliocentric theory Celsius founded nursing profession Torricelli invented barometer Copernicus considered "Father of Modern Science" Vesalius developed law of universal gravitation Newton examined the inner workings of the human body Nightingale developed metric temperature scale
Answer:
Galileo: "Father of Modern Science."
Aristotle: Geocentric theory." (The planests revolves around the earth.)
Torricelli: Invented the barometer. (An instrument which measures pressure.)
Copernicus: Heliocentric theory. (Aka, the planets revolves around the sun.)
Vesalius: Examined the inner workings of the human body
Newton: Developed law of universal gravitation.
Nightingale: Founded nursing profession.
Celsius: Developed metric temperature scale
I hope this helps! Thanks:)
A compound contains 34.5% calcium, 24.1% silicon and 41.4% oxygen by mass. What is its empirical formula?
[tex]empirical \: formula \\ = CaSiO3 \\ please \: see \: the \: attached \: picture \\ hope \: it \: helps[/tex]
Does the number of ions in solution increase, decrease, or remain constant?
It decreases at first, then increases.
It continuously increases.
It continuously decreases.
It increases at first, then decreases.
Answer:
It continuously decreases.
What does the VSEPR theory predict?
A. The chemical formula of a molecule
B. The size of a molecule
C. The shape of a molecule
D. The charge of a molecule
Answer: C
Explanation:
A P E X
The VSEPR theory predicts the shape and molecular geometry of the molecule.
What is molecular geometry?Molecular geometry can be defined as a three -dimensional arrangement of atoms which constitute the molecule.It includes parameters like bond length,bond angle and torsional angles.
It influences many properties of molecules like reactivity,polarity color,magnetism .The molecular geometry can be determined by various spectroscopic methods and diffraction methods , some of which are infrared,microwave and Raman spectroscopy.
They provide information about geometry by taking into considerations the vibrational and rotational absorbance of a substance.Neutron and electron diffraction techniques provide information about the distance between nuclei and electron density.
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Strontium, a group 2 element with an electron configuration of 1s^2 2s^2 2p^6 3s^2 3p^6 4s^2 3d^10 4p^6 5s^2 , will form a _____ ion in a chemical bond.
+1
+2
-1
-2
Answer:
Strontium, a group 2 element with an electron configuration of 1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d¹⁰ 4p⁶ 5s² , will form a +2 ion in a chemical bond.
Explanation:
An ionic bond is produced between metallic and non-metallic atoms, where electrons are completely transferred from one atom to another. During this process, one atom loses electrons and another one gains them, forming ions. Usually, the metal gives up its electrons forming a cation to the nonmetal element, which forms an anion.
So an ion is an atom or group of atoms that have an electric charge. A cation is an ion that has a positive charge.
The alkali metals in the earth (Elements IIA) lose two electrons to form a 2+ cation. Strontium is an alkali metal that loses the two electrons belonging to 5s², forming the +2 ion.
Answer:
+2
Explanation:
1. 7.85 g of sodium metal is added to 200 mL of 0.0450 M HNO3
a) Predict the mass of the precipitate
b) Predict the amount of excess reagent left over
c) Volume of gaseous product at STP conditions
Answer:
a)0.765 g
b)7.613 g
c)0.20 L
Explanation:
Consider the reaction involved;
Na(s) + HNO3(aq) ----> NaNO3(s) + H2(g)
Note that, if a hot, saturated aqueous solution of sodium nitrate was allowed to cool, solid sodium nitrate would crystallise out of the solution and this would also be classed as a precipitate. This is the case here.
Number of moles of sodium reacted= mass of sodium reacted/ molar mass of sodium
Number of moles of sodium= 7.85g/23gmol-1
Number of moles of sodium= 0.34 moles of sodium
Number of moles of acid reacted= concentration of acid × volume of acid
Number of moles of acid= 0.0450 × 200/1000
Number of moles of acid= 9×10^-3 moles
Therefore, HNO3 is the limiting reactant.
1 mole of HNO3 yield 1 mole of NaNO3
9×10^-3 moles of HNO3 yield 9×10^-3 moles of NaNO3
Hence mass of NaNO3= number of moles × molar mass
Mass of NaNO3= 9.0×10^-3 moles × 84.9947 g/mol
Mass of NaNO3= 0.765 g of NaNO3
b)
Since
1 mole of sodium metal reacts with 1 mole of HNO3
9×10^-3 moles of sodium reacts with 9×10^-3 moles of HNO3
Therefore amount of unreacted sodium metal = 0.34 moles - 9×10^-3 moles = 0.331 moles
Mass of unreacted sodium metal = 0.331 moles × 23 gmol-1= 7.613 g
c)
If 1 mole of HNO3 yields 1 mole of hydrogen gas
9×10^-3 moles of HNO3 yields 9×10^-3 moles of hydrogen gas.
1 mole of hydrogen gas occupies 22.4 L
9×10^-3 moles of hydrogen gas will occupy 9×10^-3 moles × 22.4/1 = 0.20 L
A 15.50 gram sample of a gas exerts a pressure of 1.40 atmospheres when held in an 8.00 liter at 22 °C. What is the molar mass (grams/mol) of the gas?
Answer:
33.5 g/mol
Explanation:
PV=nRT
(1.40 atm)(8.00 L)=n(0.08206)(295 K)
n=0.463 mol
15.50 g/0.463 mol=33.5 g/mol
Why you cannot add 0.3 moles of calcium fluoride directly to 1L of water to make a 0.3 M
solution ?
need help ASAP!
Answer:
Because it's not soluble in water, need to be heated acidic solution
Explanation:
Calcium Fluoride Formula: CaF2 Comprises of Ca2+ and F−
H2O = Water H+ O2- OH-
Insoluble in water
In order to dissolve a salt, you have to break apart the ions and hydrate them via a solvent.
Need to read
HSAB concept( Pearson acid-base concept) is an initialism for "hard and soft (Lewis) acids and bases"
So F- is a Halogen which is a Hard Base
And OH- is a Hard base as well
And H- is a soft base
So soft acids react best with soft bases and hard acids react best with hard bases.
Bases don't react with other bases.
Se construye una pila galvánica con una barra de cobre sumergida en una disolución 1M de cationes Fe+2 y una barra de plata sumergida en una disolución 1M de da cationes Ag+ , Calcular el potencial estándar de la celda teniendo en cuenta que a 25°C: Cu+2/Cu = -0.34V Ag+/Ag = 0.80V
Answer:
El potencial celular estándar, [tex]E_{cell}[/tex] is +0.46 V
Explanation:
Las reacciones de media célula son;
Media reacción del ánodo Cu²⁺ + 2e⁻ ↔ Cu, E ° = 0.34 V
Media reacción catódica 2Ag + 2e⁻ ⁻ 2Ag, E ° = 0.80 V
Sin embargo tenemos para hierro Fe²⁺ + 2e⁻ ↔ Fe, E ° -0.44 V
y Fe³⁺ + e⁻ ↔ Fe²⁺, E ° = 0.77 V
que es más alta que la del cobre presente, por lo tanto, el cobre se oxidará en el ánodo
Por lo tanto, en el ánodo, tendremos
Cu → Cu²⁺ + 2e⁻ (E ° = -0.34 V)
En el cátodo
2Ag + 2e⁻ → 2Ag (E ° = 0.80 V)
[tex]E_{cell} = E_c + E_a = -0.34 + 0.8 = +0.46 \, V[/tex]
El potencial celular estándar, [tex]E_{cell}[/tex] = +0.46 V
A.
B.
C.
D.
what’s could be the correct answer?
How do greenhouse gases such as CO2 and N2O contribute to an increase in Earth’s atmospheric temperature?
A.
Greenhouse gases interact with infrared photons and reflect them back to Earth’s surface.
B.
Greenhouse gases chemically react with one another, releasing heat in the process.
C.
Greenhouse gases agitate visible light photons, increasing the photons’ temperature and motion energy.
D.
Greenhouse gases generate internal heat through radioactive decay, similar to the core of Earth.
Answer:
The answer is A
Explanation:
The earth naturally maintains the heat energy balance by absorbing a sufficient amount of sunlight energy by the terrestrial land and then reverting back the excess sunlight energy back to the space. The increase in abundance of greenhouse gases in the atmosphere results in absorption of sunlight energy which contains infrared photons this is responsible for increasing the global temperature levels hence, responsible for global warming. These infrared photons are reflected to the earth surface instead of sending back to the space. This is responsible for disturbing the heat balance.
Greenhouse gases interact with infrared photons and reflect them back to earth’s surface, hence option A is correct.
How does greenhouse gases rise in earth’s atmosphere?The burning of fossil fuels, logging of forests, and raising of livestock all have a rising impact on the climate and temperature of the planet.
This increases the greenhouse effect and causes global warming by adding a significant amount of greenhouse gases to those that are already present in the atmosphere.
The earth naturally maintains the balance of heat energy by receiving enough solar energy through the terrestrial land and then returning any excess energy to space.
Therefore, greenhouse gases such as CO₂ and N₂O interact with infrared photons and reflect them back to earth’s surface.
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An acid is added to water, and a new equilibrium is established. What is the system after the acid is added? A. pH w = 1 x 10-14 B. pH w -14 C. pH > pOH and Kw = 1 x 10-14 D. pH > pOH and Kw > 1 x 10-14
Answer:
C. pH > pOH; Kw = 1.0 * 10^-14
Explanation:
The ion product of water, Kw = [H+]*[OH-] = 1.0 * 10^-14. It is a constant.
When an acid or base is added to water, its ion product does not change as it a constant. However, the relative concentrations of H+ ions and OH- ions will change depending on whether an acid or base is added to water.
When an acid is added to water, the concentration of H+ ions increases while that of OH- ions decreases, and vice versa.
Therefore, in the above situation where an acid is added to water, pH > pOH; Kw = 1.0 * 10^-14
This type of substance has a pH of 7. It will not change the color of litmus.
1. Acid
2. Base
3. Neutral
This question was just so some of y'all can get more points lol.
The three states of matter can be arranged in the increasing order of interparticle forces as 1) gas > liquid >solid 2) solid >liquid > gas 3) liquid > gas > solid pls answer fast
Answer:
OPTION 2 SOLID>LIQUID>GAS
Explanation:
because the inter molecular forces are the strongest in the solid than in liquid and than in gas
Which of the following is an example of frontier research?
A. Investigating how organisms are made of cells.
B. Testing the electrical resistance of different materials.
C. Discovering the nature of dark matter.
D. Researching how animals on the Great Plains interact.
Answer:
B. Testing the electrical resistance of different materials.
Explanation:
An example of frontier research is " Testing the electrical resistance of different materials".
What is frontier research?A frontiers Research Topic offers researchers the chance to present various viewpoints, approaches, and findings on a new or developing topic in a forum monitored by experts in the area but also published in a complete open-access journal.
What is electrical resistance?Electrical resistance towards the current stream within an electrical circuit is measured by resistance. The Greek letter omega (ω) stands for ohms, which are used to evaluate resistance.
Therefore, the correct answer will be an option (B).
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1.Mitch weighs out 67 grams of potassium (K) to make a buffer. How many moles of potassium did Dr. Hellman weigh out?
2.Which statement is NOT true about a reaction rate?
Group of answer choices
Increases with increase in reactant concentration
Increases with increasing temperature
Is the speed at which product is formed
Is the rate at which reactant is used up
All of the answers are true
3.Which statement is NOT true about a catalyst?
Group of answer choices
Are not used up during a reaction
Increases the rate of the reaction
Lowers the energy of activation
Biological catalysts are called enzymes
Are used up during a reaction
Answer:
1. 1.72 moles of potassium.
2. All of the answers are true
3. Are used up during a reaction
Explanation:
Recall that the number of moles is obtained from;
Number of moles= Mass of potassium/ molar mass of potassium
Mass of potassium= 67 g
Molar mass of potassium= 39 gmol-1
Number of moles of K= 67 g/ 39 gmol-1
Number of moles = 1.72 moles of potassium.
2. When we look at all the options, we will realize that all the options are true. The rate of reaction doubles for each 10°C rise in temperature, increasing reactant concentration increases particle collision and ultimately increases the rate of reaction. Rate of reaction deals with rate of disappearance of reactants or rate of appearance of products.
3. Catalysts remain unchanged in a chemical reaction because they do not actually participate in the reaction. Hence they are not used up in any chemical reaction.
What is the mass number of an atom that contains 19 protons, 19 electrons, and 20 neutrons?
Answer:
39
Explanation:
Total protons + total neutrons = mass number
which substance will form a solution when mixed with liquid benzene (c6h6)
Answer: [tex]I_{2} (l)[/tex]
Explanation: Because C 6 H 6 is nonpolar substance and I 2 is also nonpolar compound
According to the concept of solubility,iodine will form a solution when mixed with liquid benzene as both are non-polar substances.
What is solubility?Solubility is defined as the ability of a substance which is basically solute to form a solution with another substance. There is an extent to which a substance is soluble in a particular solvent. This is generally measured as the concentration of a solute present in a saturated solution.
The solubility mainly depends on the composition of solute and solvent ,its pH and presence of other dissolved substance. It is also dependent on temperature and pressure which is maintained.Concept of solubility is not valid for chemical reactions which are irreversible. The dependency of solubility on various factors is due to interactions between the particles, molecule or ions.
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A 10.0 g sample of an unknown liquid is vaporized at 120.0°C and 5.0 atm. The volume of the vapour is found to be 568.0 mL. The liquid is determined to be made up of 84.2% carbon and 15.8% hydrogen. What is the molecular formula for the liquid?
Answer:
molecular formula of liquid = C₈H₁₈
Explanation:
First we determine the empirical formula of the liquid:
Number of moles of each element present in the liquid = % mass / molar mass
For Carbon, (molar mass = 12.01 g/mol) : 84.2/12.01 =7.011 moles
For Hydrogen (molar mass = 1.01 g/mol) : 15.8/1.01 = 15.643
Simplest mole ratio of the elements, C : H is given by:
C = 7.011/7.011 = 1.0
H = 15.643/7.011 = 2.23
Multiplying through with 5, C:H = 5:11
Therefore, empirical formula is C₅H₁₁
The molecular mass of the liquid is next determined:
Using PV = nRT to find the number of moles of the liquid present
P = 5.0 atm; V = 568.0 mL = 0.568 L; R = 0.082 L*atmmol⁻¹ K⁻¹; T = 273 + 120 = 393 K
n = PV/RT = (5*0.568)/0.082*393
n = 0.088 moles
Molar mass of liquid = mass/no of moles = 10.0 g/ 0.088 moles = 113.63 gmol⁻¹
Molecular formula = n(empirical formula)
Molar mass of empirical formula, C₅H₁₁ = 71 gmol⁻¹
n = molecular mass/empirical mass = 113.63/71 = 1.6
Therefore, molecular formula = 1.6*(C₅H₁₁) = C₈H₁₈
