A chemistry student conducted several different procedures. Which of the following procedures best demonstrates the law of conservation of mass?
O using filter paper to separate 2 grams of solid powder from 10 grams of water
O burning 2 kilograms of wood from a pine tree leaves 0.4 kilogram of ash and soot
O evaporating sugar water leaves 5 grams of sugar and turns the water into water vapor
O combining 2 grams of copper and 4 grams of sulfur to make 6 grams of copper sulfate

Answer:

Increasing the temperature of 1 mol of C8H18(l) requires more energy

Explanation:

To answer this question, we need to define molar heat capacity that is the amount of heat required to increase in 1K the temperature of 1 mole of substance.

That means the substance with higher molar heat requires more energy to increase its temperature

Molar heat of octane, C8H18 is 255.68J/Kmol

Molar heat of water is 75.38J/Kmol

That means increasing the temperature of 1 mol of C8H18(l) requires more energy

Answer:

The quantity of heat required to melt all the ice at 0°C is 2.21 * 10⁶ J

Explanation:

Latent heat of fusion  is the heat absorbed by a unit mass of a given solid at its melting point that completely converts the solid to a liquid at the same temperature. Its unit is Joules/kg or Joules/g.

1 calorie = 4.184 Joules

Therefore , 80.0 cal/g = 80.0 cal/g * 4.184 J/cal = 334.72 J/g

1 g = 0.001 kg; Heat of fusion in J/kg = 334.72 J/g * 1g /0.001 kg = 3.35 * 10⁵ J/kg

Quantity of heat, Q = mass * latent heat of fusion of ice

quantity of heat required = 6.60 kg * 3.35 * 10⁵ J/kg

Quantity of heat required = 2.21 * 10⁶ J

Therefore, the quantity of heat required to melt all the ice at 0°C is 2.21 * 10⁶ J

Explanation:

The energy released due to breakage of bond or we can say that protons and electrons go from a structure of higher potential energy to lower potential energy. During this change, potential energy is converted to kinetic energy in form of heat.

Generally chemical potential energy is accessed in form heat, which the difference between the potential energies of reactant and product.

Answer:c

Explanation:I needed points do not take this answer for real!!

Answer:

I don't know if this is really helpful or not, but an electron weights 0.00000000000000000000000000091 grams.

Explanation:

May I have brainliest please? :)

Answer:

Melting = endothermic, solid = exothermic

Explanation:

Ok so when ice cream melts, that requires heat, so it’s Endothermic. In order to melt it, it requires heat, heat is entering. When it becomes solid again, that is exothermic because it is losing heat in order to become cool again.

Answer:

Violet only

Explination:

Violet is the only color that will eject electrons when it strikes sodium.

The colors that will eject electrons when there's a strike with sodium from the chart will be A. Violet and green.

From the complete information, William made a chart in order to illustrate the result of the experiment that was made with the photoelectric effect.

In this case, the colors that will eject electrons when they strike sodium, with the frequency threshold will be violet and green.

This was gotten from the result that the frequencies of light were lower than the frequency threshold.

Learn more about electrons on:

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Answer:

0.1765 Kg / m3

Explanation:

Mass of cholesterol = 39mg

Volume = 221mL

The concentration is given as; Mass/ Volume

Concentration = 39 / 221 = 0.1765 mg /mL

The relationship between mg / mL and Kg / m3 is;

1 mg / mL = 1 Kg / m3

This means that;

0.1765 mg /mL = 0.1765 Kg / m3

Answer:

Leeunwenhoek

Explanation:

Anton Von Leeunwenhoek was the first scientist to observe live cells and in greater details. He described spirogyra in the mid 15th century.

Since the forces equal to 0, it's balanced because the object isn't moving.

Answer:

B

Explanation:

it does not have the lone pairs.

The respective molecular geometries of the central atoms in the molecule are; trigonal planar / bent (109.5°) /tetrahedral.

We know that the shape of molecules depends on the number of electron pairs that surround the central atoms in a molecule. In the molecule (CHO)OCH3, there are three central atoms.

From the Lewis structure of the molecule (CHO)OCH3 shown in the image attached, we can clearly see that the respective geometries of the central atoms in the molecule is; trigonal planar / bent (109.5°) /tetrahedral.

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Answer:

See image attached

Explanation:

The reaction of toluene with alkaline potassium permanganate in the presence of heat leads to the oxidation of the -CH3 to give benzoic acid.

Reaction benzoic acid with HNO3/H2SO4 yields the nitronium ion (NO2+).

Recall that -COOH is a metal director and deactivated the ring towards electrophilic substitution hence the m-nitrobenzoic acid is formed.

Reaction with FeBr3/Br2 yields the product shown in the image attached.

The following are not decomposition reactions :

B. CaO + H2O ⇒ Ca(OH)2

C. 2Mg + O2 ⇒ 2MgO

The decomposition reaction is a chemical reaction shows the decomposition  of a compound into its constituent elements or compounds

General formula :

AB⇒A+B

A. KCIO3 → KCI + O2

decomposition reaction

B. CaO + H2O ⇒ Ca(OH)2

synthesis/combination reaction

C. 2Mg + O2 ⇒ 2MgO

synthesis/combination reaction

D. 2NaOH ⇒ Na2O + H2O

decomposition reaction

Answer:

an element.

Explanation:

it is the purest form

Answer:

b

Explanation:

Answer:

39.2 %

Explanation:

The following data were obtained from the question:

Mass of sample = 24 g

Mass of Cl = 14.6 g

Mass of B = 9.4 g

Percentage composition of boron =?

The percentage composition (by mass) of boron in the sample can be obtained as illustrated below:

Percentage composition of boron = mass of B /mass of sample × 100

Percentage composition of boron = 9.4/24 × 100

Percentage composition of boron = 39.2 %

Therefore, the percentage composition (by mass) of boron in the sample is 39.2 %

The percent composition of boron in this sample is 39.17 %.

The mass of chlorine = 14.60 g

The mass of Boron = 9.400g

Mass of the sample = 24.00 g

The percentage composition of boron can be calculated below:

% composition of Boron = 9.4 / 24 × 100

% composition of Boron = 940 / 24

% composition of Boron = 39.1666666667

% composition of Boron ≈ 39. 17%

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Answer:

Fire, Air, Water.

Explanation:

Matter is anything that has mass and occupies space. However, not all form of matter are visible. Air is an example of invisible matter.

Note, electricity does not have mass or does not occupy space. Therefore, electricity is not a matter.

Answer:

Fire, Air, Water

Explanation:

Electricity is the of charged particles conducting medium. However, it is the electrons that are matter, not their movement.

Matter is anything that has mass and occupies space. The flame itself is a mixture of gases and so is matter. The light and heat produced are energy not matter.

Like solids and liquids, air is matter. It has a weight and it takes up space.

Water is a liquid and liquids are one of the four fundamental states of matter.

Answer:

The amount of heat required to raise the temperature of a 32g sample of water from 8°C to 22°C is 1,874.432 J

Explanation:

Calorimetry is the measurement and calculation of the amounts of heat exchanged by a body or a system.

Sensible heat is the amount of heat that a body absorbs or releases without any changes in its physical state (phase change).

Between heat and temperature there is a direct proportional relationship. The constant of proportionality depends on the substance that constitutes the body and its mass, and is the product of the specific heat and the mass of the body. So, the equation that allows to calculate heat exchanges is:

Q = c * m * ΔT

where Q is the heat exchanged by a body of mass m, constituted by a substance of specific heat c and where ΔT is the variation in temperature.

In this case:

Replacing:

Q= 32 g* 4.184 [tex]\frac{J}{g*C}[/tex] *14 °C

Solving:

Q= 1,874.432 J

The amount of heat required to raise the temperature of a 32g sample of water from 8°C to 22°C is 1,874.432 J

Answer:

Change in velocity is -4m\s

acceleration is -2m\s^2 cause Change in velocity = final v - initial v

Explanation:

Calculating acceleration involves dividing velocity by time — or in terms of SI units, dividing the meter per second [m/s] by the second [s]. Thus the SI unit of acceleration is the meter per second squared .

-4 m/s and -2 m/s2

:-)

Answer:

3.34x10²⁴ molecules of oxygen

Explanation:

1 Mole of particles of any kind of gases or particles are always 6.022x10²³.

1 mole of electrons are 6.022x10²³ electrons

1 mole of any gas are 6.022x10²³ molecules

1 mole of oxygen are 6.022x10²³ molecules. Thus, 5.55 moles are:

Answer:

What’s the answer

Explanation:

I neeeddsdd

The number of mole of NaCl needed to react with excess Pb²⁺ to produce 45.5 g of PbCl₂ is 0.328 mole

We'll begin by calculating the number of mole in 45.5 g of PbCl₂. This can be obtained as follow:

Mass of PbCl₂ = 45.5 g

Molar mass of PbCl₂ = 207 + (35.5×2) = 278 g/mol

Mole = mass / molar mass

Mole of PbCl₂ = 45.5 / 278

2NaCl + Pb²⁺ —> PbCl₂ + 2Na⁺

From the balanced equation above,

2 moles of NaCl reacted to produce 1 mole of PbCl₂

Therefore,

Xmol of NaCl will react to produce 0.164 mole of PbCl₂ i.e

Xmol of NaCl = 2 × 0.164

Xmol of NaCl = 0.328 mole

Thus, the number of mole of NaCl needed for the reaction is 0.328 mole

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Answer:

Explanation:

A combustion  involves the reaction of a fuel with oxygen (O₂). During the reaction of combustion of hydrogen (H₂), H₂ reacts with O₂ to form water (H₂O). The balanced chemical equation is the following:

2 H₂(g) + O₂(g) → 2 H₂O(g)

According to the chemical equation, 2 moles of H₂O are obtained from the reaction of 2 moles of H₂ with 1 mol of O₂. All reactants and products are in the gaseous phase.

Answer:

b. 16, reactant side

Explanation:

Let's consider the following redox reaction.

MnO₄⁻(aq) + I⁻(aq) → Mn²⁺(aq) + I₂(s)

We can balance it using the ion-electron method.

Step 1: Identify both half-reactions

Reduction: MnO₄⁻(aq) → Mn²⁺(aq)

Oxidation: I⁻(aq) → I₂(s)

Step 2: Perform the mass balance, adding H⁺(aq) and H₂O(l) where appropriate

MnO₄⁻(aq) + 8 H⁺(aq) → Mn²⁺(aq) + 4 H₂O(l)

2 I⁻(aq) → I₂(s)

Step 3: Perform the charge balance, adding electrons where appropriate

MnO₄⁻(aq) + 8 H⁺(aq) + 5 e⁻ → Mn²⁺(aq) + 4 H₂O(l)

2 I⁻(aq) → I₂(s)  + 2 e⁻

Step 4: Multiply both half-reactions by numbers so that the number of electrons gained and lost are equal

2 × (MnO₄⁻(aq) + 8 H⁺(aq) + 5 e⁻ → Mn²⁺(aq) + 4 H₂O(l))

5 × (2 I⁻(aq) → I₂(s)  + 2 e⁻)

Step 5: Add both half-reactions and cancel what is repeated on both sides

2 MnO₄⁻(aq) + 16 H⁺(aq) + 10 e⁻ + 10 I⁻(aq) → 2 Mn²⁺(aq) + 8 H₂O(l) + 5 I₂(s)  + 10 e⁻

The balanced reaction is:

2 MnO₄⁻(aq) + 16 H⁺(aq) + 10 I⁻(aq) → 2 Mn²⁺(aq) + 8 H₂O(l) + 5 I₂(s)

Answer:

the heat energy is transformed to any kind of energy depending on what it's meant to be transformed to.

remember it cannot be destroyed so it's definitely transformed to some kinda energy

Answer: 0.923 L

Explanation: The reaction between naoh and h3po4 is:

3naoh + h3po4 —> na3po4 + 3h20

this means it requires 3 mols of naoh to make na3po4

given the concentration, 3.25 M, the equation looks like this:

3.0 mol x (1.0L/ 3.25mol) = 0.923 L

Answer:

0.56 mi/hr

Explanation:

Answer:

The elements that have the same number of energy levels or the orbitals.

Explanation:

They have he same number -- energy levels