1) In saturated limewater, [H+ ]=3.98x10-13 M.

No, two atoms that have identical mass numbers can never be considered isotopes of one another. This is due to the fact that for atoms to qualify as isotopes, they must consist of the same number of protons while differing in the number of neutrons. If two atoms share the same mass number, their proton count must also be identical, which implies these atoms cannot be isotopes of each other.

Answer:

The forward reaction will keep occurring until all NO or all NO₂ is consumed.

Clarification:

• According to Le Châtelier's principle, when a system at equilibrium experiences a disturbance from an outside source, the system will adjust to counteract this disturbance and restore equilibrium.

• Thus, removing the product (N₂O₃) from the system effectively lowers the product concentration, prompting the reaction to shift forward and generate additional product in order to alleviate the strain caused by the removal of N₂O₃.

• Consequently, the reaction will proceed forward until all of either NO or NO₂ is depleted.

Answer:

The generation of static electricity occurs when two surfaces are rubbed together. This process causes a transfer of electrons, resulting in a build-up of negative charge. For instance, when you shuffle on a carpet, the friction creates multiple contact points which allow electrons to move onto you, thus accumulating a static charge. Touching another individual or object can lead to a sudden discharge, experienced as an electric shock.

In a similar way, rubbing a balloon against your hair generates opposite static charges on both your hair and the balloon. As you gently pull the balloon away from your head, the attraction between these opposite charges can be observed, causing your hair to rise.

Materials

• Balloon

• Woolen item (like a sweater, scarf, or yarn ball)

• Stopwatch

• Wall

• Partner (optional)

Preparation

• Inflate the balloon and secure the end.

• Have your partner ready to time with the stopwatch.

Procedure

• Grip the balloon with minimal hand coverage, such as holding it with just your thumb and index finger, or by its tied neck.

• Rub the balloon on the wool item once, making sure to go in one direction only.

• Press the rubbed side of the balloon against the wall and let go. Is it adhering to the wall? If it's stuck, your partner should start the stopwatch to measure how long it stays there. If it doesn’t stick, continue to the next step.

• Briefly touch the balloon to a metal object. Why is this step necessary?

• Repeat this procedure, but each time increase the number of rubs against the woolly item, ensuring the direction remains the same (do not rub back and forth).

Observations and results

As you increase the number of times you rub the balloon on the woolly material, does the duration of its adhesion to the wall increase?

Wool is an excellent conductor; it easily relinquishes electrons. When you rub wool on a balloon, electrons move from the wool to the surface of the balloon, imparting a negative charge to the rubbed area. Balloons, made from rubber, act as insulators, which means not all areas of the balloon will have a negative charge—only where it was rubbed will have a negative charge, while the rest of the balloon remains neutral.

Once the balloon is sufficiently charged negatively by repeated rubbing, it will adhere to the wall. Though the wall typically has a neutral charge, its internal charges can realign such that a positively charged region can attract the negatively charged balloon. Since the wall is also an insulator, the charge does not dissipate instantly. However, when the balloon is in contact with a metal object, the excess electrons from the balloon flow into the metal quickly, making the balloon lose its attraction and peel away.

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An exponential decay law is generally expressed as: A = Ao * e ^ (-kt) => A/Ao = e^(-kt) Half-life time => A/Ao = 1/2, and t = 4.5 min => 1/2 = e^(-k*4.5) => ln(2) = 4.5k => k = ln(2) / 4.5 ≈ 0.154. Now substituting k, Ao = 28g, and t = 7 min to determine the remaining grams of Thallium-207 gives: A = Ao e ^ (-kt) = 28 g * e ^( -0.154 * 7) = 9.5 g. Final answer is 9.5 g.

Answer:

Number of moles of oxygen atoms that weigh the same as a glass of water = 3.12 moles

Note: This question lacks certain figures. Below is a complete similar question.

An oxygen atom weighs 2.66*10^-23 g and a glass of water weighs 0.050 kg. What is the weight of one mole of oxygen atoms? Round your result to three significant figures. How many moles of oxygen atoms have a weight equal to the weight of a glass of water? Round your answer to two significant figures.

Explanation:

One mole of a substance comprises the Avogadro number of particles, which is 6.02 * 10²³.

Hence, one mole of oxygen atoms contains 6.02*10²³ atoms.

Weight of a single oxygen atom = 2.66*10⁻²³ g

Weight of one mole of oxygen atoms = weight of a single atom multiplied by the number of atoms in one mole.

Weight of one mole of oxygen atoms = 2.66*10⁻²³ g * 6.02*10²³ = 16.01 g

A glass of water weighs = 0.050 kg or 50 g.

To calculate how many moles of oxygen atoms weigh the same as a glass of water (i.e., 50 g), the following formula is applied;

number of moles = mass/molar mass

mass of oxygen atoms = 50 g, molar mass or weight of one mole of oxygen atoms = 16.01 g

Thus, the number of moles of oxygen atoms = 50 g / 16.01 g = 3.12 moles