Answer: ionosphere
Explanation: First it bounces off a top layer of the atmosphere called the ionosphere, then it bounces back to the Earth (this is reflection. It then bounces up again to the ionosphere, and continues bouncing back again until it reaches the radio receiver. This is called a skywave, which works around 3 to 30 MHz.
Explain how the following properties change across the periodic Table from group 1 to group 2, and give reasons for the increase or decrease thereof:
a) Ionic radius
b) Ionization enthalpy
c) Density
d) Melting point
e) Electropositive character
The following properties change across the periodic Table from group 1 to group 2
a) Ionic radius - decreaseb) Ionization enthalpy - increasec) Density - increased) Melting point - increasee) Electropositive character - decreaseGroup 1 are alkali metals that have one valence electron in the outermost orbit whereas alkaline earth metals are in group 2 have two valence electrons in the outermost orbit.
a) Ionic radius:
The atomic and ionic radii of alkaline earth metals are fairly large though smaller than those of the corresponding alkali metals.b) Ionisation enthalpy:
Alkali metals have low Ionisation energy.in the case of alkaline earth metals Ionisation energy is higher compared to alkali metalsc) Density:
The alkaline earth metals are denser than the alkali metals due to the smaller size and better packing of the atoms in the crystal latticed) Melting point:
Melting points of alkaline earth metals are low but higher than those of alkali metals.e) Electropositive character:
all alkali metals are strongly Electropositive due to their low Ionisation enthalpies.alkaline earth metals are less Electropositive than alkali metals.Thus, changes in properties are:
a) Ionic radius - decreaseb) Ionization enthalpy - increasec) Density - increased) Melting point - increasee) Electropositive character - decreaseLearn more:
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Converting from the US customary system to the metric system, 16 fluid ounces is approximately equal to a) 1 gallon. O b) 160 milliliters. c) 480 milliliters. O d) 960 milliliters.
Answer:
473 ml.
Explanation:
In gallons it’s equal to 0.125
what is the free energy change G for the equilibrium between hydrogen iodine a hydrogen and iodine at 4:53
Answer:
Many chemical reactions are reversible; that is, the products of the reaction can combine to re-form the reactants. An example of a reversible reaction is that of hydrogen with iodine to form hydrogen iodide:
H2(g) + I2(g) 2 HI(g)
We can study this reversible reaction by placing hydrogen and iodine in a reaction vessel and then measuring the concentrations of H2, I2, and HI at various times after the reactants are mixed. Figure 13.8 is a plot of the concentrations of reactants and products of this reaction versus time. The concentration of hydrogen iodide increases very rapidly at first, then more slowly, and finally, after the time indicated by the vertical line marked "Equilibrium," remains constant. Similarly, the concentrations of hydrogen and iodine are large at the start of the reaction but decrease, rapidly at first, and then more slowly. Finally, they, too, become constant.
If this reaction were not reversible, the concentrations of hydrogen and iodine would have continued to decrease and the concentration of hydrogen iodide to increase. This process does not happen. Instead, as soon as any molecules of hydrogen iodide are formed, some decompose into hydrogen and iodine. Two reactions are taking place simultaneously: the formation of hydrogen iodide and its decomposition. When the concentrations of all these components become constant (at the equilibrium point in Figure 13.8), the rate of the forward reaction (H2 + I2 2 HI) must be equal to the rate of the reverse reaction (2 HI H2 + I2). A state of dynamic chemical equilibrium has then been reached, one in which two opposing reactions are proceeding at equal rates, with no net changes in concentration.
PICTURE 13.8
FIGURE 13.8 Concentration changes during the reversible reaction
H2(g) + I2(g) 2 HI as it proceeds toward equilibrium.
We have encountered this criterion for equilibrium before. In the equilibrium between a liquid and its vapor, the rate of vaporization is equal to the rate of condensation. In the equilibrium of a saturated solution with undissolved solute, the rate of dissolution is equal to the rate of precipitation. In the equilibrium of a weak acid with its ions, the rate of dissociation is equal to the rate of recombination. Note that none of these reactions is static: Two opposing changes are occurring at equal rates.
B. The Characteristics of Chemical Equilibrium
1. Equal rates
At equilibrium, the rate of the forward reaction is equal to the rate of the reverse reaction.
2. Constant concentrations
At equilibrium, the concentrations of the substances participating in the equilibrium are constant. Although individual reactant molecules may be reacting to form product molecules and individual product molecules may be reacting to re-form the reactants, the concentrations of the reactants and the products remain constant.
3. No free energy change
At equilibrium, the free energy change is zero. Neither the forward nor the reverse reaction is spontaneous and neither is favored. Consider the ice-water change. Above 0°C, ice melts spontaneously to form liquid water; G for this change is negative. Below 0°C, the change from ice to water is not spontaneous; G is positive. At 0°C, the two states are in equilibrium. The rate of melting is equal to the rate of freezing: the amount of ice and water and the amount of liquid water present remain constant, and the free energy change is zero as long as no energy is added to or subtracted from the mixture.
C. The Equilibrium Constant
In Chapter 12, we introduced the mathematical relationship between the concentrations of the components of an equilibrium, known as the equilibrium constant, Keq. We said that, for the general equation of a reversible reaction
Explanation:
sorry(: hope to help
4. A system contracts from an initial volume of 15.0 L to a final volume of 10.0 L under a constant external pressure of 0.800 atm. The value of w, in J, is?
The value of the work done in joule is 405.3 J.
We know that the work done is obtained using the relation;
w = PΔV
Where;
w = work done
P = pressure
V = volume
Now, substituting values,
w = 0.800( 15.0 - 10.0)
w = 4 atm L
Since;
1 L atm = 101.325 J
4 atm L = 4 atm L × 101.325 J/1 L atm
= 405.3 J
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Which factor is NOT important in the fossilization process?
Answer:
Things like the age of the organism, the organism's diet, style of movement (walking or swimming) do not affect how it fossilizes. Answer 2: Fossilization happens when small chunks of rock (such as sand) enter the spaces in a body or plant that would have hosted resin, air, or soft tissue, preserving the body or plant
Write a balanced chemical equation for this reaction by completing the reaction below. Add the missing products and coefficients. Do not include phases.
To balance a chemical equation you must pay attention that the algebraic equation has the same number of element atoms in reactant and the product.
A chemical equation is a term to refer to the symbolic description of a chemical reaction, that is, the written representation of symbols. For example:
2H₂ + O₂ ---> 2H₂OThe balance of an equation can be related to the law of conservation of matter, that is, the number of atoms of each element in the reactants is in the result.
Note: This question is incomplete, because the information some information is missing.
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What element is a gas at room temp, has 6 valence electrons, and is non-reactive
Answer:
Noble gases
Explanation:
Noble gases are nonreactive, nonmetallic elements in group 18 of the periodic table. As you can see in the periodic table in the figure below, noble gases include helium (He), neon (Ne), argon (Ar), krypton (Kr), xenon (Xe), and radon (Rn).18 Jun 2021
Calcium has an electronegativity value of 1.0.
Oxygen has an electronegativity value of 3.5.
What type of bond will form between the two atoms?
Answer:
ionic bond
Explanation:
Calcium gives its two valence electrons to oxygen and forms an ionic bond with oxygen. An ionic bond formed when one atom transfers one or more electrons from itself to its neighboring atom, and an ionic bond formed between the two atoms of the compound.
If an atom should form from its constituent particles,
(a) matter is lost and energy is taken in.
(b) matter is lost and energy is released. .
(c) matter is gained and energy is taken in.
(d) matter is gained and energy is released.
Answer:
(b) matter is lost and energy is released
Explanation:
When atoms are being formed from its constituent components it weighs less this is called mass defect so the answer would be (b) matter is lost and energy is released.
Find the volume of 0.170 M sulfuric acid necessary to react completely with 72.2 g sodium hydroxide.
The volume of sulphuric acid, H₂SO₄ needed for the complete reaction with 72.2 g of sodium hydroxide, NaOH is 5.31 L
We'll begin by calculating the number of mole in 72.2 g of NaOH. This can be obtained as follow:
Mass of NaOH = 72.2 g
Molar mass of NaOH = 23 + 16 + 1 = 40 g/mol
Mole of NaOH =?Mole = mass / molar mass
Mole of NaOH = 72.2 / 40
Mole of NaOH = 1.805 mole Next, we shall determine the number of mole of H₂SO₄ needed to react with 1.805 mole of NaOH.2NaOH + H₂SO₄ —> Na₂SO₄ + 2H₂O
From the balanced equation above,
2 moles of NaOH reacted with 1 mole of H₂SO₄.
Therefore,
1.805 mole of NaOH will react with = 1.805 / 2 = 0.9025 mole of H₂SO₄.
Finally, we shall determine the volume of H₂SO₄.Mole of H₂SO₄ = 0.9025 mole
Molarity of H₂SO₄ = 0.170 M
Volume of H₂SO₄ =?Volume = mole / Molarity
Volume of H₂SO₄ = 0.9025 / 0.170
Volume of H₂SO₄ = 5.31 LThus, the volume of H₂SO₄ needed for the reaction is 5.31 L
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Describing Chemical Reactions
Project: Modeling the Conservation of Mass
Answer:
Step 1: Prepare for the project.
a) Read the entire Student Guide before you begin this project.
b) If anything is unclear, be sure to ask your teacher for assistance before you begin.
c) Gather the materials you will need to complete this project.
Step 2: Review the chemical reaction.
a) The chemical reaction that you will model is shown below. Calcium oxide (CaO) is a white
solid with a crystalline structure. It is made by heating limestone, coral, sea shells, or chalk,
which are composed mainly of calcium carbonate (CaCO3). During the heating process,
carbon dioxide (CO2) is released and calcium oxide (CaO) is produced. Commercially,
calcium oxide is called lime. One of the oldest uses of lime is to make mortar, a substance
used in construction to secure bricks, stones, and blocks together.
CaCO3 CaO + CO2
Step 3: Build a model of the reactant.
a) Use gumdrops and toothpicks to build a model of CaCO3.
b) Select one color of gumdrop for calcium, a second color for carbon, and a third color for
oxygen. Be sure to include a key of your chosen color scheme with your model.
c) Use the periodic table to help you determine the number of bonds each atom will form.
Step 4: Build models of the products.
a) Use gumdrops and toothpicks to build a model of CaO and a model of CO2.
b) Be sure to use the same colors of gumdrops for calcium, carbon, and oxygen as you did in
Step 3. Include a key of your chosen color scheme with your models.
c) Use the periodic table to help you determine the number of bonds each atom will form.
Step 5: Type one to two paragraphs that describe your models and explain the conservation of
mass in the chemical reaction.
a) Create a new blank document. Type your name at the top.
b) Type one to two paragraphs that describe your models and relate them to the law of
conservation of mass. Your document should:
i. identify the names of the reactants and products in the reaction.
ii. identify the number of molecules that make up the reactants and products.
iii. identify the type and number of atoms in each molecule of the reactants and products.
iv. explain what happens during the chemical reaction.
v. explain how mass is conserved during the chemical reaction.
Step 6: Evaluate your project using this checklist.
If you can check each criterion below, you are ready to submit your project.
Did you create an accurate model of calcium carbonate (CaCO3)? Your model should include
the correct number of gumdrops for each element in calcium carbonate, consistent use of
colors for elements in calcium carbonate, and the correct number and placement of toothpicks
(bonds).
Did you create an accurate model of calcium oxide (CaO)? Your model should include the
correct number of gumdrops for each element in calcium oxide, consistent use of colors for
elements in calcium oxide, and the correct number and placement of toothpicks (bonds).
Did you create an accurate model of carbon dioxide (CO2)? Your model should include the
correct number of gumdrops for each element in carbon dioxide, consistent use of colors for
elements in carbon dioxide, and the correct number and placement of toothpicks (bonds).
Did you type one to two paragraphs that describe your models and relate them to the law of
conservation of mass? Your document should include the names of the reactants and
products in the reaction, the number of molecules that make up the reactants and products,
and the type and number of atoms in each molecule of the reactants and products. It should
also explain what happens during the chemical reaction and how mass is conserved during the reaction
Step 7: Revise and submit your project.
a) If you were unable to check off all of the requirements on the checklist, go back and make
b) When you have completed your project, submit your models to your teacher for grading.
c) Submit your document through the virtual classroom. Be sure that your name is on it.
Step 8: Clean up your workspace.
a) Clean up your workspace. Return any extra materials to your teacher and throw away any trash.
Explanation:
2. Cells are the_____________ life units on this plane
Answer:
Cell are the smallest life units on this planet
Explanation:
Mixtures of hydrogen and oxygen in varying concentrations can be sparked to produce water. Define mixture and compound, and then explain the differences between a mixture of hydrogen and oxygen and the compound dihydrogen monoxide (also known as water).
Explanation:
Mixture is the physical Combination Of two or Substance
Example
a mixture of sugar and water.
Compound is the chemical combination of two or more metals.
Example.
a mixture of hydrogen and water.
A mixture of hydrogen and oxygen forms water or H2O
whereas The dihydrogen monoxide parody involves calling water by an unfamiliar chemical name, most often "dihydrogen monoxide" (DHMO), and listing some of water's properties in a particularly alarming manner, such as accelerating corrosion (rust) and causing suffocation (drowning). The parody often calls for dihydrogen monoxide to be banned, regulated, or labeled as dangerous. It plays into chemophobia and demonstrates how a lack of scientific literacy and an exaggerated analysis can lead to misplaced fears. The parody has been used with other chemical names such as hydrogen hydroxide, dihydrogen oxide, hydroxic acid, hydric acid and oxidane.
A Mixture of hydrogen and oxygen in varying concentrations can be sparked to produce water. This is formed due to the property of chemical combination.
A Mixture is the physical Combination Of two or Substance whereas a Compound is the chemical combination of two or more metals.
Example of a mixture is a mixture of sugar and water. And, Example of an compound is A mixture of hydrogen and oxygen forms water or H₂O
Water is also called as dihydrogen monoxide. The prefix mono and di are used to indicate a single atom and combination of two atoms respectively. Some of its properties includes such as accelerating corrosion (rust) and causing suffocation (drowning).
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Identify the strongest intermolecular force that is likely to affect each of the samples described below.
A mixture of chlorine gas (Cl) and fluorine gas (F): V London dispersion forces
COMPLETE
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A mixture of hydrogen sulfide (H2S) and hydrogen chloride (HCI): V dipole-dipole interactions
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Selection
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this
hydrogen bonding
A mixture of water (H2O) and ammonia (NH3):
Answer:
A mixture of chlorine gas (Cl2) and fluorine gas (F2):
✔ London dispersion forces
Explanation:
Part C
Describe the shape of the graph showed in part B.
(Is it like- a normal shape??)
This graph shows a straight line.
Answer:
The graph is a straight line that angles upward.
So My friend has started her you know what and she scared to call her mom what should I do I'm sorry if this question is personal anything but I'm kind of confused cuz she's scared to call her mom her mom is gone so she needs some advice the best person who got the best answer will receive a brainly and 50 more points
Answer: so I was really scared to tell my mom and I was always thinking about how should I tell here but she should tell her mom an just said I think I started my thing her mom wont get mad she got it to and every girl goes thru that so your not alone
Explanation; she does not have to tell her mom but her mom could helpo her and give her tips
Answer:
Tell her to calm down and tell her mum because her mom knows better and would be able to put her through better than anyone could have ever.
Mechanical waves travel fastest through
A -Solid
B -Liquid
C -Gas
D -Vacuum
Answer:
A-Solid
Explanation:
Waves travel faster in solids & slowest in gases
What are the dependent and independent variables in this experiment? How are outside factors being controlled in this experiment to make sure that the results test only the dependent variable?
Answer:
1. An independent variable is manipulated, or changed. The dependent, or responding variable, changes based on the independent variable. The dependent variable is examined.
2. It is a controlled experiment.
Explanation:
In a controlled experiment all variables are kept the same, except for the one being tested, which is called the experimental variable , or independent variable . This group is the experimental group . The group that is not affected by the experimental variable is the control group .
Very often a graph will be used to analyze the results of the experiment. The independent/experimental variable is placed on the x-axis and the dependent variable is placed on the y-axis. The dependent variable is what is measured as a result of the application of the experimental variable.
A variable that is independent is altered. Based on the independent variable, the responding variable, or dependent variable, alters. Examining the dependent variable. The experiment is carefully controlled.
What is an independent variable ?In mathematical modeling, statistical modeling, and experimental sciences, there are dependent and independent variables. Dependent variables get their name because, during an experiment, their values are investigated under the presumption or requirement that they are dependent on the values of other variables due to some law or rule.
A variable that is independent is precisely what it sounds like. It is a stand-alone variable that is unaffected by the other variables you are attempting to assess. Age, for instance, could be an independent variable.
When doing an experiment, the independent variable is what you alter, and the dependent variable is what changes as a result of that change. This is an easy way to conceive of independent and dependent variables.
Thus, based on the independent variable, the responding variable, or dependent variable, alters.
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For the given reactions determine if the entropy increases or decreases.
A) 2 KClO3 (s)⇌2 KCl (s)+3 O2 (g)
B) CoCl2 (s)+6 H2O (g)⇌CoCl2⋅6H2O
Entropy increases in reaction 1 due to increase in the number of particles while entropy decreases in reaction 2 due to decrease in the number of particles.
Entropy refers to the degree of disorderliness in a system. The higher the entropy, the more disorderly the system is and the lower the entropy, the less disorderly the system is. We must note that entropy increases with increase in the number of particles.
In the reaction, 2 KClO3 (s)⇌2 KCl (s)+3 O2 (g), entropy increases because one of the products is a gas and the number of particles increases from left to right. In the second reaction, CoCl2 (s)+6 H2O (g)⇌CoCl2⋅6H2O, entropy decreases because the number of particles decreases.
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Dont need work pls help
what is the mass number of an atom with 3 protons,4 nuetrons, and 3 electrons
Answer:
Neon 10, mass: 20.18
Explanation:
Oil does not dissolve in water because
Answer:
Because oil have apolar molecules, while water have polar molecules
4.What volume of hydrogen gas at STP is produced when 2.5 grams of zinc react with an
excess of hydrochloric acid?
Answer:
0.86
Explanation:
1mol of Zn has mass of 65.39g.The amount of Zn is 2.5g65.39g/mol=0.038mol.
The amount of H2 produced is the same as the amount of Zn consumed (0.038mol).
1mol of ideal gas will occupy 22.4L at STP.
The H2 will occupy 0.038mol×22.4L/mol=0.86L
.
the amount of solute dissolved in a solvent
A. Concentration.
B.alloy
C.mixture
D.solution
Answer:
solution
Explanation:
solvent +solute =solution
What is the use of GMO?
Some benefits of genetic engineering in agriculture are increased crop yields, reduced costs for food or drug production, reduced need for pesticides, enhanced nutrient composition and food quality, resistance to pests and disease, greater food security, and medical benefits to the world's growing population.
Insect resistance: Corn
Herbicide tolerance: Soybean
Where did the atoms come from in the first place?
Answer:
All the carbon atoms in the human body were created in the stars. Elementary particles, such as protons, were formed during the "big bang"; that amazing moment about 14 billion years ago in which the universe got it's start.
What’s the answer to this? Pls help
Answer:
First choice
Explanation:
The process of returning mines to their original state is called ________________________.
Answer:
Mine Reclamation.Explanation:
The process of returning mines to their original state is called Mine Reclamation. HOPE THIS HELPS :)Convert 1.36x10 to standard form
Answer:
13.6 is the correct answer written in standard form.
Explanation:
1.36, move the decimal once to the right to get 13.6
Answer:
13.6
Explanation:
The standard form is 13.6
an alloy composed of tin, lead, and cadmium is analyzed. the mole ratio of sn:pb is 2.73:1.00, and the mass ratio of pb:cd is 1.78:1.00. what is the mass percent composition of pb in the alloy
This problem is describe the mole-ratio composition of an allow composed by tin, lead and cadmium. Ratios are given as Sn:Pb 2.73:1.00 and Pb:Cd is 1.78:1.00, and we are asked to calculate the mass percent compositon of Pb in the allow.
In this case, according to the given information, it turns out possible realize that the following number of moles are present in the alloy, according to the aforementioned ratios:
[tex]2.73mol Sn\\\\1.00molPb\\\\\frac{1.00molPb*1.00molCd}{1.78molPb}= 0.562molCd[/tex]
Next, we calculate the masses by using each metal's atomic mass:
[tex]m_{Sn}=2.73mol*\frac{118.7g}{1mol}=324.05g\\\\ m_{Pb}=1.00mol*\frac{207.2g}{1mol}=207.2g\\\\m_{Cd}=0.562mol*\frac{112.4g}{1mol}=63.2g[/tex]
Thus, the mass percent composition of each metal is shown below:
[tex]\%Sn=\frac{324.05g}{324.05g+207.2g+63.2g} *100\%=54.5\%\\\\\%Pb=\frac{207.2g}{324.05g+207.2g+63.2g} *100\%=34.9\%\\\\\%Cd=\frac{63.2}{324.05g+207.2g+63.2g} *100\%=10.6\%[/tex]
So that of lead is 34.9 %.
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