chemistry screen shot below plzzzzzzz help i've been stuck forever

Answer:  28.2 g of ²⁶Mg can be isolated from the 9.87 mole sample of natural magnesium

Explanation:

we know that natural abundance of ²⁶Mg is 11.01 %

therefore moles of ²⁶Mg isolated from 9.87 mole sample of natural magnesium will be :

( 11.01 x 9.87 mol) / 100  = 1.09 mol

so

mass of ²⁶Mg = mol x molar mass

⇒ 1.09 mol x 25.9826 g/mol

= 28.2 g

Therefore 28.2 g of ²⁶Mg can be isolated from the 9.87 mole sample of natural magnesium

Answer:

2HCl + Ba(OH)2 = BaCl2 + 2H2O

Explanation:

To solve such this we must know the concept of  neutralization reactions. Therefore, the  balanced equation for the neutralization of hydrochloric acid by barium hydroxide is 2HCl + Ba(OH)[tex]_2[/tex] [tex]\rightarrow[/tex] BaCl[tex]_2[/tex] + 2H[tex]_2[/tex]O.

Chemical reaction is a process in which two or more than two molecules collide in right orientation and energy to form a new chemical compound. The mass of the overall reaction should be conserved.

Neutralization is an acid-base reaction in which an acid reacts with just a base to produce salt and water. The pH of a neutralizing solution is determined by the acid strength and concentrations of the reactants. The balanced equation for neutralization of hydrochloric acid by barium hydroxide can be written as

2HCl + Ba(OH)[tex]_2[/tex] [tex]\rightarrow[/tex] BaCl[tex]_2[/tex] + 2H[tex]_2[/tex]O

Therefore, the balanced equation for the neutralization of hydrochloric acid by barium hydroxide is 2HCl + Ba(OH)[tex]_2[/tex] [tex]\rightarrow[/tex] BaCl[tex]_2[/tex] + 2H[tex]_2[/tex]O.

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Answer:

18.1 mi/h

Explanation:

Step 1: Given data

Distance traveled (d): 100 yd

Time elapsed (t): 11.3 s

Step 2: Convert "d" to miles

We will use the relationship 1 mi = 1,760 yd.

100 yd × (1 mi/1,760 yd) = 0.0568 mi

Step 3: Convert "t" to hours

We will use the relationship 1 h = 3,600 s.

11.3 s × (1 h/3,600 s) = 3.14 × 10⁻³ h

Step 4: Calculate the average speed (s)

We will use the following expression.

s = d / t

s = 0.0568 mi / 3.14 × 10⁻³ h

s = 18.1 mi/h

Answer:

You use the number of electrons in an aluminum atom to determine how many protons are in its nucleus because the atomic number of aluminum, 13, tells you how many electrons and protons they are. Then you can the  number of neutrons by subtract it's atomic number by its mass, 27, which will result in the number of neutrons, 14.

Explanation:

The atomic number of aluminum is 13 and mass number of aluminum is 27. This helps us to tell us how many protons, electrons and neutrons are there in its nucleus.

The atomic number of a chemical element  is defined as the charge number of an atomic nuclei.

The mass number of an atom tells us the number of protons and neutrons are there in an atoms.

The number of electron surrounding the nucleus is equal to number of protons present in the nucleus. Hence there is 13 electrons  and 13 protons in the nucleus.

Now we can calculate number of neutrons present in the nucleus.

Mass number = number of protons + number of neutrons

Number of neutrons = mass number - number of protons

                                   = 27 - 13 = 14

So number of neutrons is 14 , and  number of protons is 13.

Thus, atomic number of aluminum is 13 and mass number of aluminum is 27. This helps us to tell us how many protons, electrons and neutrons are there in its nucleus.

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Answer: it's known as heat transfer

Explanation: Heat always moves from a warmer substance to a cooler substance. For example, holding an ice cube will make your hand begin to feel cold in a few seconds. But is the coldness in the ice cube moving to your hand? No! Since cold is the absence of heat, it’s the heat in your hand that moves to the ice cube. This is one of the ways that heat is transferred.

According to the concept of thermal energy, heat transfer in a circular motion is called as convection.

Thermal energy is defined as a type of energy which is contained within a system which is responsible for temperature rise.Heat is a type of thermal energy.It is concerned with the first law of thermodynamics.

Thermal energy arises from friction and drag.It includes the internal energy or enthalpy of a body of matter and radiation.It is related to internal energy and heat .It arises when a substance whose molecules or atoms are vibrating faster.

These vibrating molecules and atoms collide and as a result of which heat is generated in a substance , more the collision of particles , higher is the thermal energy.There are three types of thermal energy.

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Answer:

If I lived in Flint, Michigan, it would be important for me to understand chemistry because of the high contamination levels of water in the city, in order to know how to help to solve this issue and to avoid any potential harm to my health.

There is an ongoing drinking water issue since 2014 in Flint, Michigan. In April 2014, the Flint authorities changed the source of water from the Detroit Water and Sewage Department, which takes it from Lake Huron and the Detroit River, to the Flint River for cost-effective reasons. This led to a series of water quality problems culminating in the presence of lead, creating a serious threat to public health.

Answer:

It will produce iron(III) sulphate ,nitrogen dioxide and water

Explanation:

hope it helps you☺️

if I'm correct do mark my answer as brainliest

C) It contains the same number of electrons and protons.

Answer:

E) None of these

Explanation:

For this question, we must remember the definition of a chiral carbon. In the chiral carbons, we have four different groups around the carbon.

So, an achiral molecule would be a molecule that does not have chiral carbons. That is, in an achiral molecule in all carbons we have at least one repeating group.

In all the molecules, which we have in the question, we have absolute configuration. That is, we have chiral carbons. In molecule A we have two chiral carbons (R and R), in molecule b we have two chiral carbons (R and S), in molecule c we have two chiral carbons (S and S) and in molecule d we have two chiral carbons (R and S). Therefore in all molecules, we have chiral carbons.

Now, if we analyze molecules a and c, we have a plane of symmetry. If we have a plane of symmetry, even though there are chiral carbons, there will be no optical activity. That is, these molecules do not have the ability to deflect polarized light despite having chiral carbons. Therefore molecules a and c are meso compounds.

But optical activity is not related to chirality.

See figure 1 to further explanations

I hope it helps!

The temperature in the chromosphere varies between about 4000 K at the bottom (the so-called temperature minimum) and 8000 K at the top (6700 and 14,000 degrees F, 3700 and 7700 degrees C), so in this layer (and higher layers) it actually gets hotter if you go further away from the Sun

Answer:

independent: type of liquid

dependent: growth of plant

control: time

constant: time

constant: time

hypothesis: If I water the plant with water, it will grow the most because water is the liquid that sustains life on earth.

Explanation:

The following that is not one of the four groups of organic compounds is a monosaccharide. The correct option is D.

Any of a vast group of chemical compounds known as organic compounds contain one or more carbon atoms that are covalently connected to atoms. Organic compounds are made up of carbon and hydrogen, and oxygen.

Carbohydrates, lipids, proteins, nucleic acids, and nucleotides are organic compounds.  Due to their presence of both carbon and hydrogen, these substances are referred to as organic.

Monosaccharides are the single unit of carbohydrates. They join to form polymers of carbohydrates. They are glucose, fructose, etc. It is a single unit of carbohydrates. It is not one of the organic compound.

Thus, the correct option is D) monosaccharides.

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The question is incomplete. Your most probably complete question is given below:

A) carbohydrates D) monosaccharides B) lipids E) proteins C) nucleic acids

Answer:

1 kiloliter = 1,000,000 milliliters

45 × 1,000,000

45 KL = 45,000,000 ML

Answer:

0.617

Explanation:

The experimental value is the average of all the values recorded:

(2.65 + 2.73 + 2.77)/3 = 2.72

Then use the equation:

(2.72 - 2.7)/ 2.7 x 100 = 0.617

Answer:

Mass of hydrogen in 42 gram of J = 8.4

Explanation:

Given:

Amount of compound J = 10 gram

Mass ratio[lithium (Li): Hydrogen (H)] = 8:2

Find:

Mass of hydrogen in 42 gram of J

Computation:

Mass of hydrogen in 10 gram of J = [2 / 10] 10

Mass of hydrogen in 10 gram of J = 2 gram

Mass of hydrogen in 42 gram of J = [2 / 10] 42

Mass of hydrogen in 42 gram of J = 8.4

Answer:

Sodium nitrate and CH4

Explanation:

Acids have an "H" at the start and bases have a hydroxide (OH)

Explanation:

H2 (g) + 2NO(g) → N2O(g) + H2O(g)

Trial 1 Trial 2 Trial 3

H2 (M) 0.30 0.60 0.60

NO (M) 0.35 0.35 0.70

Rate (M*s) 2.835 x 10^-3 1.134 x 10^-2 2.268 x 10^-2

a. What is the order with respect to H2?

Comparing trial 1 and 2, the conc of H2 is doubled, the rate of the reaction increased by a factor f 4. This means the rate is in second order with respect to H2.

b. What is the order with respect to NO?

Comparing Trial 2 and 3, the concentration of NO is doubled, the rate of the reaction increased by a factor of 2. This means the rate is in first order with respect to NO.

c. What is the rate equation for this reaction?

The rate equation is given as;

rate = k [H2]²[NO]

d. Calculate the rate constant for the reaction.

Taking trial 1;

2.835 x 10^-3 = k (0.30)²(0.35)

k = 2.835 x 10^-3  / 0.0315 = 90  x 10^-3

k = 0.09 L2 mol-2 s-1

Answer:

(Chemical compound and indicated bond in attachment).

C) This is a triple bond between two carbons in which a sigma bond arises from sp- sp overlap and two pi bonds are formed by side-to-side overlap of unhybridized p orbitals on each carbon.

Explanation:

Alkynes are hydrocarbons that contain carbon-carbon triple bonds. Each carbon atom is bound to the other two atoms, and there are no free valence electrons. Each carbon atom needs two hybrid orbitals to form the skeleton of sigma bonds. The hybridization of the s orbital with a p orbital generates two hybrid orbitals, oriented at 180º of separation for each carbon atom. The overlap of these hybrid orbitals sp with the s orbitals from the hydrogen produces the skeleton of sigma bonds.

The result of the overlap of the two remaining unhybridized p orbitals of each atom of carbon is the formation of two pi bonds. These orbitals overlap in right angles with each other, forming a pi bond with electronic density above and below the sigma bond and the other with electronic density in front of and behind the sigma bond. The form of these pi bonds is such that they combine to form a cylinder of electron density that "wraps" the sigma bond between the two carbon atoms.

Answer:

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12.9 Theoretical Yield and Percent Yield

FlexBooks® 2.0  >  CK-12 Chemistry For High School  >  Theoretical Yield and Percent Yield

It is best to have high yields for chemical reactions

Can we save some money?

The world of pharmaceutical production is an expensive one. Many drugs have several steps in their synthesis and use costly chemicals. A great deal of research takes place to develop better ways to make drugs faster and more efficiently. Studying how much of a compound is produced in any given reaction is an important part of cost control.

Percent Yield

Chemical reactions in the real world don’t always go exactly as planned on paper. In the course of an experiment, many things will contribute to the formation of less product than would be predicted. Besides spills and other experimental errors, there are usually losses due to an incomplete reaction, undesirable side reactions, etc. Chemists need a measurement that indicates how successful a reaction has been. This measurement is called the percent yield.

To compute the percent yield, it is first necessary to determine how much of the product should be formed based on stoichiometry. This is called the theoretical yield, the maximum amount of product that could be formed from the given amounts of reactants. The actual yield is the amount of product that is actually formed when the reaction is carried out in the laboratory. The percent yield is the ratio of the actual yield to the theoretical yield, expressed as a percentage.

Percent yield is very important in the manufacture of products. Much time and money is spent improving the percent yield for chemical production. When complex chemicals are synthesized by many different reactions, one step with a low percent yield can quickly cause a large waste of reactants and unnecessary expense.

Typically, percent yields are understandably less than 100% because of the reasons indicated earlier. However, percent yields greater than 100% are possible if the measured product of the reaction contains impurities that cause its mass to be greater than it actually would be if the product was pure. When a chemist synthesizes a desired chemical, he or she is always careful to purify the products of the reaction.

Sample Problem: Calculating the Theoretical Yield and the Percent Yield

Potassium chlorate decomposes upon slight heating in the presence of a catalyst according to the reaction below:

In a certain experiment, 40.0 g KClO3 is heated until it completely decomposes. What is the theoretical yield of oxygen gas? The experiment is performed and the oxygen gas is collected and its mass is found to be 14.9 g. What is the percent yield for the reaction?

First, we will calculate the theoretical yield based on the stoichiometry.

Step 1: List the known quantities and plan the problem.

Known

given: mass of KClO3 = 40.0 g

molar mass KClO3 = 122.55 g/mol

molar mass O2 = 32.00 g/mol

Unknown

theoretical yield O2 = ? g

Apply stoichiometry to convert from the mass of a reactant to the mass of a product:

Step 2: Solve.

The theoretical yield of O2 is 15.7 g.

Step 3: Think about your result.

The mass of oxygen gas must be less than the 40.0 g of potassium chlorate that was decomposed.

Now, we use the actual yield and the theoretical yield to calculate the percent yield.

Step 1: List the known quantities and plan the problem.

Known

Actual yield = 14.9 g

Theoretical yield = 15.7 g (from Part 12.11A)

Unknown

Percent yield = ? %

Use the percent yield equation above.

Step 2: Solve.

Step 3: Think about your result.

Since the actual yield is slightly less than the theoretical yield, the percent yield is just under 100%.

Summary

Theoretical yield is calculated based on the stoichiometry of the chemical equation.

The actual yield is experimentally determined.

The percent yield is determined by calculating the ratio of actual yield/theoretical yield.

Review

What do we need in order to calculate theoretical yield?

If I spill some of the product before I weigh it, how will that affect the actual yield?

How will spilling some of the product affect the percent yield?

I make a product and weigh it before it is dry. How will that affect the actual yield?

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Explanation:

Answer:

c. HF can participate in hydrogen bonding.

Explanation:

The boiling points of substances  often reflect the strength of the intermolecular forces operating among the molecules.

If it takes more energy to  separate molecules of HF than of the rest of the hydrogen halides because HF molecules are held  together by stronger intermolecular forces, then the boiling point of HF will be higher than  that of all the hydrogen halides.

A particularly strong  type of intermolecular attraction is called the hydrogen bond, which is a special type of dipole-dipole interaction between the hydrogen atom in a polar bond, such as N-H, O-H, or F-H, and an electronegative O, N, or F atom.

Following are the calculation to the atomic mass:

Given:

Please find the attached file.

To find:

atomic mass=?

Solution:

Following are the calculation to the atomic mass:

[tex]\to 89.90470\times (0.5293)+90.90565\times (0.1154)+91.90504\times (0.1765)+93.90632\times (0.1788)\\\\\to 47.58655771 +10.49051201 +16.22123956+16.790450016\\\\\to 91.0887593\approx 91.0887\ amu \\\\[/tex]

Therefore, the final answer is "91.0887".

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Answer:

Answer is no because,

Explanation:

Iodine is LESS REACTIVE than the elements above it in group 17 (fluorine, chlorine and bromine) it still forms compounds with many other elements. Although iodine is a non-metal, it displays some METALLIC properties. Xenon is one of the inert or noble gases and is odorless, colorless, tasteless and chemically NON REACTIVE

PLEASE MARK BRAINLIEST

Answer:

helicona

throated carib

eulampis jugularis

Answer:

The percentages

Explanation:

Quantitative data are numbers, while qualitative data are characteristics. So I think that the numbers are your answer.

Hope that helps!

Answer: 2 Al + 3 Cl₂ → 2 AlCl₃

Explanation:

To balance equations, you want to have the same amount of each element. We know 2 Al + 3 Cl₂ → 2 AlCl₃ is the balanced equation because there are equal amounts of each element on both sides. There are 2 Al and 6 Cl.

Answer:

D. Water

Explanation:

Specific heat is defined as the amount of heat you need to add to a substance per unit of mass to increase its temperature in 1°C.

That means if you have the same mass of substances, the one with the higherst specific heat is the one that requires the most amount of heat to increase its temperature by one degree Celsius.

As you can see, water is the material with the highest specific heat doing the material that requires the most heat.

Right answer:

Answer: D

Explanation:  I took the test

Answer:

[tex]\huge\boxed{\sf Ice\ Added = 210\ g}[/tex]

Explanation:

Weight of glass of water before adding ice = 40 g

Weight of glass of water after adding ice = 250 g

Ice Added = 250 g - 40 g

Ice Added = 210 g

Answer:

Explanation:

For pH of a buffer solution , the equation is

pH = pKa + log [ A⁻ ] / [ HA ]

Putting the values

7 = -  log 56 x 10⁻¹⁰ +  log [ NH₃ ] / [ NH₄⁺]

7 = 10 - log 56 + log [ NH₃ ] / [ NH₄⁺]

- 3 + 1.748 =  log [ NH₃ ] / [ NH₄⁺]

log [ NH₃ ] / [ NH₄⁺] = - 1.25

[ NH₃ ] / [ NH₄⁺] = [tex]10^{-1.25}[/tex]

Required ratio = [tex]10^{-1.25}[/tex]

2 )

In the formation of NH₄⁺ , generally HCl acid is required . A little bit of excess HCl will change the pH required . So , this mixture is a poor choice for getting pH 7 for a buffer solution .

Answer:

C&D all living things are composed of cells

The basic unit of life is a cell

Answer:

d ≈ 0.098 g/mL

Explanation:

The density of a substance can be found by dividing the mass by the volume.

d=m/v

The mass of the substance is 0.221 grams and the volume is 2.25 milliliters.

m= 0.221 g

v= 2.25 mL

Substitute the values into the formula.

d= 0.221 g / 2.25 mL

Divide

d= 0.098222222 g/mL

Let’s round to the nearest thousandth. The 2 in the ten thousandths tells us to keep the 8 in the thousandth place.

d ≈ 0.098 g/mL

The density of the substance is about 0.098 grams per milliliter.

Answer:

Explanation:5.70