Elements are identified by their atomic number because
A.the mass of an element changes over time.
B.the number of protons remains constant.
C.atoms of the same element have different numbers of neutrons.
D.elements in a group react in a similar way.

Answer: C

Explanation: 3 mol O2 ⇒ 2 mol CO2

O2 reacts to produce 5 mol of CO2 = (3 * 5)/2 = 7.5 mol O2

Considering the definition of pH, the pH is 6.35 and the solution is acidic.

pH is the Hydrogen Potential and it is a measure of acidity or alkalinity. pH indicates the amount of hydrogen ions present in a solution or substance.

Mathematically, pH is calculated as the negative base 10 logarithm of the activity of hydrogen ions:

pH= - log [H⁺]

The numerical scale that measures the pH of substances includes the numbers from 0 to 14. The pH value 7 corresponds to neutral substances. Acidic substances are those with a pH lower than 7, while basic substances have a pH higher than 7.

In this case, being [H⁺]=4.5×10⁻⁷ M, you can replace this value in the definition of pH:

pH= -log (4.5×10⁻⁷ M)

Solving:

pH= 6.35

Finally, the pH is lower than 7, the solution is acidic.

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Answer:

13g of CO₂ is the maximum amount that could be produced

Explanation:

The reaction of hexane with oxygen is:  

C₆H₁₄ + 19/2O₂ → 6CO₂ + 7H₂O  

Where 19/2 moles of oxygen react per mole of C₆H₁₄

To solve this question we need to find theoretical yield finding limiting reactant :

Moles C₆H₁₄:  

4.3g C₆H₁₄ * (1mol / 86.18g) = 0.0499 moles  

Moles O₂:  

25.8g * (1mol / 32g) = 0.806 moles  

For a complete reaction of 0.0499 moles of C₆H₁₄ are needed:

0.0499 moles of C₆H₁₄ * (19/2 mol O₂ / 1mol C₆H₁₄) = 0.474 moles of O₂.

As there are 0.806 moles, O₂ is in excess and C₆H₁₄ is limiting reactant

In theoretical yield, the moles of hexane added = 6Moles of CO₂ produced. Moles of CO₂ are:

0.0499 moles C₆H₁₄ * (6mol CO₂ / 1mol C₆H₁₄) = 0.299 moles CO₂

In grams:

0.299 moles CO₂ * (44.01g / mol) = 13g CO₂

Answer:

180 g Ca

General Formulas and Concepts:

Chemistry - Atomic Structure

Explanation:

Step 1: Define

4.4 mol Ca

Step 2: Identify Conversions

Molar Mass of Ca - 40.08 g/mol

Step 3: Convert

\(4.4 \ mol \ Ca(\frac{40.08 \ g \ Ca}{1 \ mol \ Ca} )\) = 176.352 g Ca

Step 4: Check

We are given 2 sig figs. Follow sig fig rules and round.

176.352 g Ca ≈ 180 g Ca

Answer:

I might be late but when red paint and blue paint mix to become purple. its a physical change, so its C

Explanation:

From the two examples provided, the chemical formula Sg represents an element.

It is defined as a substance which cannot be broken down further into any other substance. Each element is made up of its own type of atom. Due to this reason all elements are different from one another.

Elements can be classified as metals and non-metals. Metals are shiny and conduct electricity and are all solids at room temperature except mercury. Non-metals do not conduct electricity and are mostly gases at room temperature except carbon and sulfur.

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Because a higher water level translates into a lower atmospheric pressure, the wet CO2 gas pressure is lower than the atmospheric pressure.

Wet CO2 gas pressure is therefore lower than air pressure outside the collection cylinder if the water level inside is higher than the water level outside.

By displacing water, a gas created during a chemical reaction can be collected. As a result of being gathered over water, the gas is not pure and is instead combined with water vapor. By deducting the contribution of the water vapor, the amount of the desired gas can be calculated using Dalton's law.

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Answer: twice the momentum

Explanation:

(a) The number of moles of Ag⁺ that reacted is 0.05 mmoles and moles of Cl- that reacted is 0.05 mmoles.

(b) The number of moles of AgCl(s) formed is 0.05 moles

(c) The molarity of Ag⁺ after the reaction = 0.0 M

(d) The molarity of NO₃⁻ after the reaction is 0.25 M

The number of moles of Ag and Cl- that reacted is calculated as follows from the equation of the reaction:

AgNO₃ (aq) + NaCl (aq) ---> AgCl (s) + NaNO₃ (aq)

(a) The number of moles of Ag and Cl- that reacted:

Moles of Ag⁺ = 0.5 * 0.1

Moles of Ag⁺ = 0.05 mmoles

Moles of Ag⁺ that reacted = 0.05 mmoles

Moles of Cl⁻ = 0.5 * 0.1

Moles of Cl⁻ = 0.05 mmoles

Moles of Cl⁻ that reacted = 0.05 mmoles

(b) The number of moles of AgCl(s) formed.

Moles of AgCl that formed = 0.05 moles

(c) Since there are no more Ag⁺ ions in the mixture, the molarity of Ag⁺ after the reaction = 0 moles

(d) The molarity of NO₃⁻ after the reaction.

Moles of NO₃⁻ = 0.5 * 0.1

Moles of NO₃⁻ = 0.05 moles

Volume of mixture = 0.2 mL

The molarity of NO₃⁻ after the reaction = 0.05/0.2

The molarity of NO₃⁻ after the reaction = 0.25 M

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Answer:

V2 = 0.998L

v2 = 0.000998mL

Explanation:

P1 = 392mmHg

V1 = 690mL

T1 = -15.1°C = 257.9k

P2 = 0.700atm = 532mmHg

V2 = ?

T2 = 233°C = 506K

using general gas equation

P1V1/T1 = P2V2/T2

(392 x 690.0 x 10^-³)/257.9 =(532 x V2)/506

1.05=(532 x V2)/506

1.05 x 506 =(532 x V2)

531.3 =(532 x V2)

V2 = 531.3/532

V2 = 0.998L

v2 = 0.000998mL

Following are the effects of acid rain.

What is Acid Rain?

Acid rain is caused by the accumulation of nitric and sulfuric acids in the atmosphere. These compounds are strong acids and are very soluble in water, dissolving in droplets in clouds.

Limestone effect:

Calcium carbonate, [Ca][CO3], is a very common mineral. A limestone is a well-known form of calcium carbonate. The acid contained in acid rain reacts with carbonate ions and promotes the dissolution of calcium carbonate.

This will create a bicarbonate solution. The presence of limestone and other calcium carbonates in lakes and streams helps maintain a constant pH as the mineral reacts with excess acidity. However, acid rain can eventually exceed the buffering capacity of surface waters.

How does acid rain affect buildings made of marble and limestone?

It is mainly affected in 2 ways: dissolution and alteration. Calcite dissolves when sulfuric, sulfuric and nitric acids in polluted air react with calcite in marble and limestone. Exposed areas of buildings and statues show rough surfaces, worn materials, and loss of sculptural detail. Stoneface material can be lost anywhere or only in more reactive areas.

Hence, this is how acid rain affects.

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Answer:

\(\boxed{\mathrm{substance}}\)

Explanation:

The term used by particular kind of matter is called substance.

A substance is a particular kind of matter because it has physical properties.

Answer:

Explanation:

HF + H2O reacts to form H3O+ (hydronium ion) and F- (fluoride ion).

Answer:

D - Matter

Explanation:

Matter is defined as anything that has mass and takes up space. Matter is basically liquid soilds and gasses!

(I hope this helps :>)

An equation which obey the law of conservation of mass is defined as the balanced chemical equation. According to law of conservation of mass, mass can neither be created nor be destroyed. The products are LiNO₃ and K. The correct options are B and D.

The substance which appears on the left hand side of the equation is defined as the reactants whereas the substance which are present on the right hand side are called products.

The reaction between 'Li' and KNO₃ is given as:

Li (s) + KNO₃ (aq) → LiNO₃ + K

Thus the correct options are B and D.

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Answer:

1. Because a Francium atom is deeper down the alkali metals, it is much easier to lose a valence electron.

2. A fluorine atom can easily gain a valence electron, but it could not easily lose a valence electron because it is one electron away from filling the outer shell

Explanation:

The answer is the explanation

Answer:

B - Idea models are not typically used to predict natural disasters.

Answer:

Here is the order of increasing boiling point and increasing solubility in water for the substances you listed:

-2-Methylpropane < -2-butanol < -2-pentanol < -2-propanol

Explanation:

-2-Methylpropane has the lowest boiling point and is the least soluble in water.

-2-butanol has a higher boiling point than -2-methylpropane, but lower than -2-pentanol and -2-propanol

-2-pentanol has a higher boiling point than -2-butanol and -2-methylpropane, but lower than -2-propanol

-2-propanol has the highest boiling point and is the most soluble in water.

Please note that this is a general trend and there can be variations depending on factors such as pressure, purity of the substance, and temperature.

There is zero formal charges on nitrogen in NOCl and sulfur in SF6.

The Lewis structure of NOCl is shown in the image attached. The NOCl molecule is bent or angular. The N - O - Cl bond angle in the molecule is about 113°.The molecule is polar, the formal charge on nitrogen is calculated as follows;

FC = 5 - 2 - 6/2 = 0

The Lewis structure of SF6 is shown in the image attached. The molecule is octahedral  hence the bond angle in the molecule is 90°. The molecule is nonpolar because it is symmetrical. The formal charge on sulfur atom is zero.

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Answer:

heat is mesured in calories and also joules

Explanation:

The volume of the ethanol that has a density of ethanol is 0.789 g/cm³ is 209.13cm³.

The volume of a substance can be calculated by dividing the mass of the substance by its density as follows:

Volume = mass ÷ density

According to this question, the density of ethanol is 0.789 g/cm³. A flask holds 165.0 g of ethanol and the volume can be calculated as follows:

Volume = 165.0g ÷ 0.789g/cm³

Volume = 209.13cm³

Therefore, the volume of the ethanol that has a density of ethanol is 0.789 g/cm³ is 209.13cm³.

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The shape of the molecule with two atoms bonded to a third central atom with no lone pairs on the central atom is Linear.

Hence the correct option is (A)- linear

As given, the central atom has no lone pairs and two atoms bonded to the central atom.

Therefore the shape of the molecule is linear.

For example, let's take the example of CO₂. Here, the central atom is C and has four valence electrons. C uses 1 pair o electrons to form a double bond with each atom of O. Hence, C uses a total of 4 electrons to form a double bond with the O atom. No lone pair is left with carbon to create distortion in the molecule.

Therefore, the shape of the molecule will be linear.

So, the correct option is A.

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Answer:

Filter it

Explanation:

Answer:

It would take approximately

64.0

s

given those data.

Explanation:

21.3

s

=

0.693

k

∴

k

≈

3.25

⋅

10

−

2

s

−

1

ln

(

1

8

)

=

−

3.25

⋅

10

−

2

s

−

1

⋅

t

∴

t

≈

64.0

s

Each equation I used is assuming this reaction's kinetics are of the first order, which is cited. The first equation is a simplified version for the half life of a first order reactant, and the second equation is the general equation for first order reactions in chemical kinetics.

With an Ag concentration of 0.020 M and a Pb2+ concentration of

0.0010 M, Only PbSO4(s) will precipitate,

Option C is correct

Generally, the equation for the Chemical Reaction  is mathematically given as

Ag2SO4--->2Ag++SO4^{-2}

Where

PbSO4--->Pb2+ +SO4^{-2}

Therefore

Ag2SO4=[0.02^2[0.001]]

Ag2SO4=4*10^{-7}

and

PbSO4=[0.001^2[0.001]]

PbSO4=4*10^{-6}

In conclusion,Since PbSO4>>PAg2SO4, Only PbSO4(s) will precipitate.

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Precision relates to the consistency and reproducibility of measurements, while accuracy reflects how close measurements are to the true value.

Precision and accuracy are two important concepts in the context of errors in measurements. While they both pertain to the quality of data, they refer to different aspects.

Precision refers to the degree of consistency or reproducibility in a series of measurements. It reflects the scatter or spread of data points around the average value. If the measurements have low scatter and are tightly clustered, they are considered precise. On the other hand, if the measurements have a high scatter and are widely dispersed, they are considered imprecise.

Accuracy, on the other hand, refers to the closeness of measurements to the true or target value. It represents how well the measured values align with the actual value. Accuracy is achieved when measurements have a small systematic or constant error, which is the difference between the average measured value and the true value.

Errors in measurements can be classified into two types: random errors and systematic errors.

Random errors are associated with the inherent limitations of measurement instruments or fluctuations in the measurement process. They lead to imprecise data and affect the precision of measurements. Random errors can be reduced by repeating measurements and calculating the average to minimize the effect of individual errors.

Systematic errors, on the other hand, are caused by consistent biases or inaccuracies in the measurement process. They affect the accuracy of measurements and lead to a deviation from the true value. Systematic errors can arise from factors such as instrumental calibration issues, environmental conditions, or experimental techniques. These errors need to be identified and minimized to improve the accuracy of measurements.

In summary, precision refers to the degree of consistency or reproducibility of measurements, while accuracy refers to the closeness of measurements to the true value. Random errors affect precision, while systematic errors affect accuracy. To ensure high-quality measurements, both precision and accuracy need to be considered and appropriate techniques should be employed to minimize errors.

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