Question 2(Multiple Choice Worth 4 points) (01.01 MC) Dominic and Eva are using the same type of stopwatches to measure the time it takes for a chemical reaction to occur. They each use the same stopwatch to measure the time. These are their results: Person Trial 1 Dominic 78 seconds Eva 81 seconds Why are their results unreliable and can lead to a pseudoscientific claim? They did not repeat their tests multiple times. They used the same type of stopwatch. They did not change the reactants in their chemical reactions. Only one person should have collected the data.

If 1 kg of mass disappeared, this only means that all of those mass was converted to energy. We can actually compute for the energy using the formula:

E = m c^2

where m is mass and c is speed of light:

E = 1 kg * (3 x 10^8 m/s^2)2

E = 9 x 10^16 J

Answer:

3 x 10^8 J of energy is produced

a p e x verified

Answer: Option (A) is the correct answer.

Explanation:

Chemical changes are defined as the change which tend to show difference in chemical composition of a substance.

For example, toxicity, reactivity, combustion etc are all chemical properties.

A chemical change will always lead to the formation of a new compound and this change is irreversible in nature by any physical means.

When we explode a fire cracker then it is a chemical change.

On the other hand, a change which is unable to bring any difference in chemical composition of a substance is known as a physical change.

For example, change in shape, size, mass, volume etc are all physical properties.

Physical changes are reversible in nature.

Thus, we can conclude that out of the given options an exploding firecracker indicates a chemical change.

The final temperature of a 10.0 g aluminum block initially at 25.0°C after applying 435 joules of energy is c) 73.3°C. The change in temperature is found to be 48.3°C.

To determine the final temperature of a 10.0 g aluminum block originally at 25.0°C after applying 435 joules of energy to it, we can use the formula for heat transfer:

Q = mcΔT, where

First, rearrange the formula to solve for the change in temperature (ΔT):

ΔT = Q / (mc)

Substituting the known values:

ΔT = 435 J / (0.01 kg * 900 J/kg∙K) = 435 / 9 = 48.3°C

Since the initial temperature is 25.0°C, the final temperature will be:

Final temperature = Initial temperature + ΔT = 25.0°C + 48.3°C = 73.3°C

Therefore, the final temperature of the aluminum block is c) 73.3°C.

Complete Question:

Determine the final temp of a 10.0 g aluminum block originally at 25°C if you apply 435 J of energy to it. The specific heat of aluminum is 0.89 J/g°C.

a) 57.9°C

b) 64.3°C

c) 73.3°C

d) 83.2°C

In this exercise we are going to deal with the solubility of a solution in which the amount of diluted sodium is 718 g.

Solutions are homogeneous systems formed by mixing two or more substances. Solutions are made up of two components: the solute, which is the one that dissolves and is found in the smallest amount, and the solvent, which is the component in the largest amount and acts by dissolving the solute.

In this way we have that:

Making the calculus we have:

[tex](35.89g / 100 mL) * (2000) = 718 g[/tex]

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We use the formula:

ΔP = (ΔH / ΔV) ln(T2 / T1)

where,

ΔH = change in enthalpy from solid to liquid = 4810 J/mol

ΔV = change in volume from solid to liquid = 0.55 cm^3/mol

T2 = 620 K, T1 = 600 K

So,

ΔP = (4810 / 0.55) ln(620 / 600)

ΔP = 286.76 J/cm^3

or converting to atm:

ΔP = 2830 atm

Answer:

ΔP = (ΔH / ΔV) ln(T2 / T1)

Explanation:

Because a water molecule has a negative end and a positive end, it displays unequal electrons sharing which gives the water molecule a partial negative charge near its oxygen atom and a partial positive charge near its hydrogen atoms.

Water is a fluid substance which has no taste, odor, or transparency, and it is composed of the oxygen atom that attracts electrons strongly than the nuclei of the hydrogen atoms.

The oxygen in water molecule is more electro negative  than hydrogen which results in the development of a partial negative charge on the oxygen atom and a partial positive charge on the hydrogen atom.

Water shows  cohesive property in which the attraction of molecules for other molecules is called as cohesion.

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The number of moles of potassium is [tex]\boxed{{\text{3 mol}}}[/tex].

Further Explanation:

Mole is the S.I. unit. The number of moles is calculated as the ratio of mass of the compound to that of molar mass of the compound.

Molar mass also known as molecular weight is the sum of the total mass in grams of all the atoms that make up a mole of a particular molecule that is the mass of 1 mole of a compound. Its S.I unit is g/mol.

The expression to relate number of moles, mass and molar mass of compound is as follows:

[tex]{\text{Number of moles}}=\dfrac{{{\text{mass of the compound}}}}{{{\text{molar mass of the compound}}}}[/tex]

The formula to calculate number of moles of potassium is as follows:

[tex]{\text{Number of moles of potassium}}=\dfrac{{{\text{Given mass of potassium}}}}{{{\text{molar mass of potassium}}}}[/tex]   ......(1)

The given mass of potassium is 117.3 g.

Molar mass of potassium is 39.0983 g/mol.

Substitute 117.3 g for given mass of potassium and 39.0983 g/mol for molar mass of potassium in equation (1) to calculate the number of moles of potassium.

[tex]\begin{aligned}{\text{Number of moles of potassium}}&=\frac{{{\text{117}}{\text{.3 g}}}}{{{\text{39}}{\text{.0983 g/mol}}}}\\&= {\text{3}}{\text{.0001 mol}}\\&\approx{\text{3}}\;{\text{mol}}\\\end{aligned}[/tex]

Hence, the number of moles of potassium in 117.3 g is 3 mol.

Learn more:

1. Balanced the chemical equationhttps://brainly.com/question/11200282

2. How many moles of ammonia is producedhttps://brainly.com/question/1527872

Answer details:

Grade: High School

Subject: Chemistry

Chapter: Mole concept

Keywords: Potassium, number of moles, molar mass, compound, ratio, mass, 117.3 grams, 39.0983 g/mol, 3.0001 mol, and 3 mol.

The chemical formula is composed of hydrogen and oxygen where the two atoms are bonded through hydrogen bond type of bonding. In this pair, the oxygen is the more electronegative atom hence the electrons are more directed to it. Because of this, this creates electron polarity which affects the chemical property of water.

Final answer:

The chemical formula of H₂O results in a polar molecule with strong hydrogen bonds, which give water its unique properties like high heat capacity, solvent capabilities, and ice's lower density than liquid water.

Explanation:

The chemical formula of water, H₂O, influences its chemical properties due to the arrangement of its atoms and the polar nature of its molecules. Each water molecule consists of one oxygen atom bonded to two hydrogen atoms. The oxygen atom draws electrons closer than the hydrogen atoms, creating a molecule with a negative charge near the oxygen and a positive charge near the hydrogens, establishing a polar structure. This polarity leads to strong hydrogen bonding between water molecules, resulting in many of water’s unique properties, such as high surface tension, high boiling point, and its role as a universal solvent.

Chemical Structure and Properties of Water

Water's polarity and hydrogen bonds are essential for its ability to dissolve various substances, which makes it a key player in chemical reactions and in biological systems. Due to these characteristics, water can contribute to the stabilization of ecosystems and the regulation of climate. The structure of water molecules also accounts for the fact that ice is less dense than liquid water, which is why ice floats. These properties are all rooted in the molecular structure of water, dictated by its chemical formula, H₂O.