CanvasX &Question 16Consider the reaction: 4Na(s) + O2(8) → 2Na2O(s)

To find out how many significant numbers there are in a number we can rely on a few rules:

1. Non-zero digits are always significant

2. Any zeros between non-zero digits are significant

3. Final zeros or trailing zeros are significant if they come after the non-zero numbers in a decimal number situation

Example: .500 and .632000

In this question, we have:

0.0016/0.849 = 0.0019, this is the correct value with the correct number of significant figures

Answer

acids and bases are both corrosive furthermore both will conduct electricity depending on the strength of the acid or base

C is the correct option

In this question, we have a reaction between silver nitrate and potassium chloride, which will have the following chemical formula and also the following product:

AgNO3 (aq) + KCl (aq) --> AgCl (s) + KNO3 (aq)

Now we need to identify the ions that are components of the precipitate that was formed in this reaction

A precipitate is a product of a reaction that is not soluble in water in the conditions given in the reaction, therefore the precipitate will be a solid product of the reaction. The solid of the reaction is AgCl, therefore this is the precipitate

Now the ions that compose AgCl are Ag+ and Cl-, the answer will be the 3rd option

Green column - Alkaline earth metals

Red column - Alkali metals

Purple column - Lanthanides and actinides

Blue column - Transition metals

The red block are made up of group 1 elements and these elements are known as Alkali metals.

The green column are the group 2 elements in the periodic table and are known as the Alkali earth metals.

For the blue columns, they are element from group 3 to 10 and they are known as the transition metals.

For the purple column, they are Lanthanides and actinides

The hardness of water sample with 35.1 ppm Mg²⁺ and 65.8 ppm Ca²⁺ is 6.215 ppm is 100.9 ppm

Hardness of water is a parameter which is defined by the amount of dissolved minerals in the water like calcium and magnesium. Thus, hard water would have high amount of dissolved minerals in the water. They are sweeter in taste and are good for bones and teeth because of the mineral content

Total hardness of water = Degree of hardness of Mg ²⁺ + Degree of hardness of Ca ²⁺

Degree of hardness Mg ²⁺ = 35.1 ppm

Degree of hardness of Ca ²⁺ = 65.8 ppm

Total hardness = 35.1 + 65.8 = 100.9 ppm

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A legend of the North star goes as follows:

The North star is a star that sits directly above the North pole of the earth. It is also known as Polaris.

The North star is especially significant in that the North star is an ever-present star in the skies. It neither rises nor sets unlike other stars in the skies.

Because of this special feature of the North star, it serves as a guiding beacon in the skies for travelers. Also, several legends have been told about the North star.

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The question requires us to comment on what happens to the atoms in a chemical reaction considering the Law of Conservation of Mass.

The Law of Conservation of Mass states that mass is neither created nor destroyed in a chemical reaction. In other words, although the atoms in the reactants rearrange in order to form the products, the mass of both products and reactants must be the same.

Therefore, we can say that, considering the Law of Conservation of Mass, the atoms at the start of a chemical reaction are rearranged compared to the atoms at the end of the reaction, but the mass of reactants and products do not change.

Step 1 - Understanding percentual concentration

To express the concentration of a substance as a percentual concentration, we just need to divide its mass by the total mass:

Step 2 - Calculating the concentration in the pill

We want to calculate the concentration of Mg in the pill. Therefore, we'll divide its mass by the total mass of the pill:

Answer: the concentration of Mg in the pill is 6.8%

Ethylmethylamine is a secondary amine, that has one ethyl group attached to the amine group and one methyl group, which is a also attached to the amine group.

It is represented by:

Nevertheless it can be represented by CH3CH2NHCH3.

It means that the correct answer is c. Both.

Step 1

Density is defined as:

D = mass of the platinum brick/volume of the platinum brick

D = m/V

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Step 2

Information provided:

D = 21.45 g/mL

V = 150.0 mL

m = unknown

Price per grams of Pt = 31.86 $/g of Pt

Symbol for platinum = Pt (please, look at the periodic table)

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Step 3

How much should the brick weigh if it’s is really platinum?

From D = m/V

=> D x V = m

=> 21.45 g/mL x 150.0 mL = 3218 g approx.

------

And how much money?

3218 g of Pt x 31.86 $/g of Pt = $99,660 approx.

Answer:

3218 g

$99,660

The answer is -2219.9 kJ/mol

Answer:

89.58 moles of MnO3 are produced.

Explanation:

1st) From the balanced reaction we know that the relation between O2 and MnO3 is that 3 moles of O2 produces 2 moles of MnO3.

2nd) To build the equation, we must build a path from the given value of 4.30kg of O2 to moles of MnO3. So, it is important to figure out the relations that we need to build the equation.

The order to build the equation is:

• Start with, the given value of ,4.30kg of O2,.

• We need to convert kg to grams, so we need the realtion between kg and g: ,1kg=1000g,.

• To convert the grams of oxygen to moles, we need to use the molar mass of O2: ,32g/1mol,.

• We need to use the relation between O2 and MnO3 from the balanced equation: ,3 moles of O2, produces, 2 moles of MnO3,.

So, 89.58 moles of MnO3 are produced.

This element is nonmetal and appears in the periodic table.

The number that represents the position of the elements is called, the atomic number, it also represents the number of protons = numbers of electrons an atom has.

Answer: D. the atomic number

Answer:

0.9933

(Text Text Text)

Answer:

C = 9 mol

Explanation:

Reaction: A + 2B ---> C

We want to find the moles of C.

Given: moles of A = 9 mol.

To solve this problem we will need to use stoichiometry.

A is the limiting reagent because it has a coefficient of 1 and B has a coefficient of 2.

The molar ratio between A and C is 1:1 therefore for every 9 moles of A that react, 9 moles of C will be produced.

Answer:CO2

Explanation:

A trick that is quick and easy to use when telling covalent bonds from ionic bonds is to look at the atoms that are bonding. If there is a metal involved, then it is ionic bonding (hence AgF, NaCl. and K2S are not covalent bonding as Ag, Na, and K are all metals.

But to be more specific, ionic bonding happens when two ionic or polar atoms (atoms with non-neutral charges,) come together to balance out their charges (as negative charges will be attracted to positive charges and vice versa); the fancy term for this is electrostatic forces. They (usually) give up electrons to another atom, but do not share electrons. Covalent bonding happens when atoms actually share electrons and have their atomic orbitals overlap, meaning that the electrons actually travel through the surrounding volume of both atoms. Ionic bonded atoms will also separate into ions when in a solvent.

They give us the reactions with their respective products and reactants. To balance a reaction we must bear in mind that matter is neither created nor destroyed, it only transforms. So the mass that we have in the reactants must be the same in the products. We verify this by counting the atoms of each element on each side of the reaction.

In the first reaction we have nitrogen and hydrogen. We have 2 nitrogens and 2 hydrogens in the reactants. We start off-balanced in nitrogen, so we place coefficient 2 in the NH3 molecule to get 2NH3. Now that we have 2 nitrogens and 6 hydrogens in the products, we must balance the hydrogen in the reactants. For that, we place the coefficient 3 in the H2 in such a way that there will be 6 hydrogen atoms in the reactants. The equation is balanced and will be:

We do this same procedure for the other two equations. We count the atoms, we put the coefficients so that the number of atoms is conserved and we count again until the number of atoms of each element is the same on each side of the reaction. For the other two reactions we have:

Answer:

A

Explanation:

it is easy and doesn't take a long time

Answer:

Explanation:

As the cell has a copper strip like the anode and a coin or nail (we can consider this like it is nickel) like the cathode, we can write both half-reactions:

• Copper half-reaction,:

In the copper anode, the oxidation reaction takes place. This is the positive terminal.

• Nickel half-reaction,:

In the nickel cathode, the reduction reaction takes place. This is the negative terminal.

The direction of the electron flow always go from the anode to the cathode.

Step 1

Data provided:

The reaction: 4Al + 3O2 => 2Al2O3 (balanced)

The limiting reactant Al (it is said that Al reacts completely)

Mass of Al = 42.6 g

The actual yield = 57.8 g Al2O3

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Step 2

Data needed: the molar mass of Al (26.9 g/mol) and Al2O3 (101.9 g/mol)

The theoretical yield:

4 x 26.9 g Al ------- 2 x 101.9 g Al2O3

42.6 g Al ------- X = 80.7 g Al2O3 = theoretical yield

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Step 3

% yield = (actual yield/theoretical yield) x 100 = (57.8 g/80.7 g) x 100 = 71.6 %

(this is the closest value for one of the options, 71.8 %)

Answer: 71.8 %

The proton acceptor (base) in this following reaction is  H₃0⁺

Here given reaction is

HCI + H₂O  → CH + H₃O⁺

A proton is a subatomic particle found in the nucleus of every atom so in that reaction H₃0⁺ is the  proton acceptor because protonic acid is the proton donor H⁺ so H₃0⁺ must be bronsted acid and OH⁻ because it accept the proton is a therefore a bronsted base and a lewis acid is by definition an electron pair acceptor and a lewis base is an electron pair donor

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According to the given statement one mole of potassium has a mass of 39.1 g.

Each element's atomic weight is listed in a periodic table along with how many grams (or an Avogadro number) are needed to make one mole of atoms. Since potassium has an atomic weight of 39.0983 g/mole, a mole of potassium weighs 39.1 g.

Avogadro's number, which is equal to 6.02214076 * 10²³, is the quantity of units in one mole of any material (defined as its molecular weight in grams). Depending on the substance and the nature of the reaction, the units could be electrons, atoms, ions, or molecules.

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Answer

wiring

Explanation

Ancient humans did make jewelry, weapons and tools by smoltering ore, however, they did not make wires, hence there was no electricity in many mnay years ago.

General nucleus and electron attraction explained

We can say this:

The net positive charge from the nucleus (remember that protons are in the nucleus) that an electron can feel attraction from, is the effective nuclear charge. The core electrons (electrons are on shells around the nucleus) are said to shield the valence electrons from the full attractive forces of the pro

The volume of 0.875 mol/dm³ NaOH solution needed to make up a 100.0 ml of a diluted solution with a concentration of 0.235 mol/dm³ NaOH is 73.15 mL.

Given that :

molarity M1 = 0.875 mol/ dm³

M2 = 0.235 mol/ dm³

volume V2 = 100mL

using the formula , we get

M1 V1 = M2 V2

substituting the values in the formula we get :

0.875 × V1 = 0.235 × 100 mL

V1 = 26.857 mL

the volume added = V2 - V1 = 100 mL - 26.85 = 73.15

Thus, The volume of 0.875 mol/dm³ NaOH solution needed to make up a 100.0 ml of a diluted solution with a concentration of 0.235 mol/dm³ NaOH is 73.15 mL.

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Answer:

Explanation: 2 C19H34O2(l) + 53 O2(g) ==> 38 CO2(g) + 34 H2O(l) ... balanced equation

∆Hcombustion

∆H = ∑∆Hf products - ∑∆Hf reactants

∆H = [(38 x -393.5) + (34 x -285.8)] - (2 x -645.7) = (-14,953 + -9717) - (-1291)

∆H = -24,670 + 1291

∆H = 25,961 kJ

(be sure to check the math)

The formula for calculating the amount of heat energy absorbed is given as:

Given the following

• mass m = 50.0g

• Heat energy Q = 7490 Joules

• change in temperature = 80 -10= 70 degrees celsius

Substitute

Hence the specific heat capacity of methanol is 2.14J/gC

The functional group of the given molecule is located at one of the extremes of it, it is:

This functional group is a carbonyl derived group known as amide. We can recognized because of the carbon that has a double bond with the oxygen and at the same time has a simple bond with nitrogen.

It means that the correct answer is amide.

ANSWER

The pressure of the gas is 281.25 mmHg

EXPLANATION

Given that;

The initial pressure of the gas is 75 mmHg

The intial temperature of the gas is 80K

The final temperature of the gas is 27 degrees Celcius

Follow the steps below to find the final pressure of the gas

Step 1; Convert the final temperature to degrees kelvin

Step 2; Apply the Gay Lussac's law