Tools, Technology, and measurement

Answer:

c

Explanation:

Answer:2.9 grams

Explanation:i had this question

Ammonia (\(NH_3\)) and ammonium chloride (\(NH_4Cl\)) mixture could be a useful buffer in a solution. Option C

A buffer is a solution that can resist changes in pH when small amounts of acid or base are added. It consists of a weak acid and its conjugate base or a weak base and its conjugate acid. The buffer system works by the principle of Le Chatelier's principle, where the equilibrium is shifted to counteract the changes caused by the addition of an acid or a base.

In option A, acetic acid (\(CH_3CO_2H\)) is a weak acid, but hydrochloric acid (HCl) is a strong acid. This combination does not form a buffer because HCl is completely dissociated in water and cannot provide a significant concentration of its conjugate base.

Option B consists of sodium hydroxide (NaOH), which is a strong base, and elemental sodium (Na), which is a metal. This combination does not form a buffer as there is no weak acid-base pair involved.

Option D contains acetic acid (\(CH_3CO_2H\)), a weak acid, and ammonia (\(NH_3\)), a weak base. Although they are weak acid and base, they do not form a buffer system together as they are both weak acids or bases and lack the required conjugate acid-base pair.

Option C, ammonia (\(NH_3\)), is a weak base, and ammonium chloride (\(NH_4Cl\)) is its conjugate acid. This combination can form a buffer system. When ammonia reacts with water, it forms ammonium ions (NH4+) and hydroxide ions (OH-).

The ammonium ions act as the weak acid, while the ammonia acts as the weak base. The addition of a small amount of acid will be counteracted by the ammonium ions, and the addition of a small amount of base will be counteracted by the ammonia, thus maintaining the pH of the solution relatively stable.

Therefore, option C, consisting of ammonia (\(NH_3\)) and ammonium chloride (\(NH_4Cl\)), is the suitable mixture that could be a useful buffer in a solution.

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Answer:

It speeds around the Sun every 88 days, traveling through space at nearly 29 miles (47 kilometers) per second, faster than any other planet. Mercury spins slowly on its axis and completes one rotation every 59 Earth days.

Answer:

Weight

Explanation:

WHen talking about weight you’re referring to the force exerted to lift if, but when you’re talking about mass it’s just how much it weighs but not how much it takes to lift it.

Answer: - your answer should be the Dependent Variable

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The gas law that is calculated with the pressure and volume variables at a constant temperature is Boyle's Law. Boyle's Law states that the pressure (P) of a gas is inversely proportional to its volume (V) when temperature (T) is held constant.

Mathematically, it is expressed as P₁V₁ = P₂V₂, where P₁ and V₁ represent the initial pressure and volume, and P₂ and V₂ represent the final pressure and volume.According to Boyle's Law, if the volume of a gas is reduced while keeping the temperature constant, the pressure will increase proportionally.

Similarly, if the volume is increased, the pressure will decrease. This relationship holds as long as the temperature remains constant throughout the process. Boyle's Law is one of the fundamental gas laws and provides insights into the behavior of gases under changing pressure and volume conditions at a constant temperature.

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Answer:

1 qualiative physical  

2 qualiative   chemical

3 quantitative physcial

4 quantiative chemical

5qualiative   physcial

6quatiative    chemcial

7quanatiative physcial

8 qualiative   chemical

9quatliate  physcial

The vessel will not explode since the new gas pressure is less than 3 atm.

The pressure when the temperature of a given volume of nitrogen gas is heated is calculated using the formula given below:

where;

Solving for P₂

P₂ = P₁ * T₂ / T₁

P₂ = 0.836 * (680 + 273) / (20 + 273)

P₂ = 2.72 atm

The new pressure is less than 3 atm.

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Answer:

12.26%

Explanation:

MM K = 39.1 g/mol

MM K2CO3 . 10H2O = 2x39.1 + 12.01 + 3 x 15.99 + 10 x 18.02= 318.38 g/mol

% by weight = (MM K/MM K2CO3.10H2O ) x 100= (39.1/318.8)  x 100=12.26 %

The percent composition by weight of potassium in potassium carbonate decahydrate is 13.98%

Let's represent the chemical formula of the compound as follows;

potassium carbonate decahydrate = CH₂0KO₁₃

The molecular mass of the compound can be calculated as follows:

mass of potassium = 39 g

Therefore,

% mass of potassium = 39 / 279 × 100

% mass of potassium = 3900 / 279

% mass of potassium = 13.9784946237

% mass of potassium = 13.98 %

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Answer: B

Explanation: a calcium ion has a charge of +2 because it has 2 more protons than electrons giving it a positive charge instead of neutral or negative.

The pH at the equivalence point in the titration of 50.0 ml of 0.300 M CH₃COOH with 0.3 M NaOH is 8.61.

At the equivalence point in the titration of CH₃COOH with NaOH, the pH is determined by the hydrolysis of the salt formed, which is CH3COO⁻ and Na+.

The equation for the hydrolysis reaction is:

CH3COO⁻ + H2O ⇌ CH3COOH + OH⁻
We can use the Ka value for CH₃COOH to find the Kb value for CH3COO⁻ using the equation:

Kw = Ka x Kb

Where Kw is the ion product constant for water (1.0 x 10⁻¹⁴).
Kb = Kw/Ka

= (1.0 x 10⁻¹⁴)/(1.8 x 10⁻⁵)

= 5.56 x 10⁻¹⁰
Now we can use the Kb value to find the concentration of OH⁻ at the equivalence point using the equation:

Kb = ([OH⁻][CH3COOH])/[CH3COO⁻].

Since the concentrations of CH3COOH and CH3COO⁻ are equal at the equivalence point, we can simplify the equation to Kb = ([OH⁻]²)/[CH₃COO⁻].
Hence,
[OH-] = \(\sqrt{Kb(CH3COO-)}\)

=\(\sqrt{5.56(10^{-10})(0.3) }\)

= 4.06 x 10⁻⁶ M
Use the concentration of OH⁻ to find the pH at the equivalence point using the equation pOH = -log[OH-] and the relationship pH + pOH = 14.
pOH = -log(4.06 x 10⁻⁶)

= 5.39
pH = 14 - 5.39

= 8.61
Therefore, the pH at the equivalence point in the titration of 50.0 ml of 0.300 M CH3COOH with 0.3 M NaOH is 8.61.

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Answer:

wow 15 points is alot

Explanation:

An increased temperature generally causes a reaction to occur faster rather than slower. Therefore option C is correct.

The increased temperature leads to a higher average kinetic energy of the molecules, which results in more frequent and energetic collisions between the reactant particles.

This increased collision frequency and energy facilitate the breaking of chemical bonds and the formation of new bonds, leading to an accelerated reaction rate.

When the temperature is raised, the kinetic energy of the molecules increases. This means that the individual molecules move faster and possess a greater amount of energy. As a result, the molecules collide more frequently and with higher energy, enhancing the likelihood of successful collisions that lead to a reaction.

In summary, an increased temperature leads to a faster reaction rate by increasing the average kinetic energy of the particles, causing more frequent and energetic collisions.

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The amount, in mL, of the suspension that should be given to an infant weighing 17 lb will be 1.16 mL

0.8 mL of the liquid contains 80.0 mg of the drug.

The recommended dose is 15 mg per kg of body weight

The infant to be given the drug weighs 17 lb.

First, let's convert the weight of the infant to kg.

1 lb = 453.59 g

17 lb =       453.59 x 17/1

                   = 7711.03 g

1000 g = 1 kg

7711.03 g = 7711.03 x 1/1000

               = 7.711 kg

So, the baby's weight is 7.711 kg.

The drug dose for the baby can thus be calculated as:

15 mg x 7.711 = 115.67 mg

But 0.8 mL of the drug contains only 80.0 mg. How many mL will contain 115.67 mg?

                   0.8 x 115.67/ 80.0 = 1.16 mL

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Answer:NaF is ionic. NF3 is covalent. SiF4 is ionic. CaF2 is Ionic and  NH4F is also ionic. Ionic compounds transfer electrons whereas covalent compounds share electrons hence the word "co". Also, ionic compounds are formed with metal and nonmetal. Where a covalent is with 2 nonmetals. Only ionic compounds would produce fluoride in water because ionic compounds can dissolve in water and covalent compounds cant.

The compounds that can be used for the release of fluorine in water are NaF, \(\rm SiF_4\), \(\rm CaF_2\), and \(\rm NH_4F\).

The ionic compounds are formed by the transfer of electrons between the atoms of the compounds. The ionic bonds are weaker and are easy to dissociate in the aqueous solution.

The covalent compounds are formed by the sharing of electrons between the atoms. Since there is sharing, there has been a strong bond, that has been hard to dissociate.

The Mayor has to release Fluoride in the water, thus ionic compounds are preferred that have the easy release of fluorine.

From the given compounds:

Thus the compounds that can be used for the release of fluorine in water are NaF, \(\rm SiF_4\), \(\rm CaF_2\), and \(\rm NH_4F\).

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Answer:

Axel: Much of the water is in the air around us.

Explanation:

When a puddle of water forms on the ground, it indicates that much of the ground around it is saturated with water and as such, the water would not readily soak into the ground. Also, since the puddle was found in a park, it is not likely that the water has gone into a stream, river, pond, lake, or ocean.

Since, the day was a sunny, it means that the heat from the sun has caused the evaporation of the water molecules. However, the water vapor molecules do not just immediately rise up to the atmosphere to form clouds nor do they cease to exist, rather it is dispersed in the air around the surroundings and beyond. Formation of clouds by water vapor takes days to happen.

Also, the water has not changed to fog either as they form usually at cooler temperatures.

The heat released is 439.5 J during the reaction.

The heat released can be calculated using the formula:

where q is the heat released, m is the mass of the solution, C is the specific heat of water, and ΔT is the change in temperature.

First, we need to calculate the total mass of the solution:

The density of water is 1 g/mL, so the mass of the solution is 35 g.

Next, we can calculate the change in temperature:

Finally, we can substitute these values into the formula:

Therefore, 439.5 J of heat was released during the reaction.

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Answer:

Theoretical Yield = 13.35 g of Fe2O3

Explanation:

Check the conversion to get to the limiting reaction below!

Answer:

B. Isotope 2

Explanation:

Isotopes can be defined as the atom of an element that has the same number of protons but different number of neutrons. This ultimately implies that, the isotopes of an element have the same atomic number (number of protons) but different atomic mass (number of nucleons).

Basically, the atomic mass of any chemical element found in the periodic table is equal to the weighted average of all its isotopes. Therefore, the isotope with the closest mass to the weighted average would be the most abundant.

In this scenario, a new element was discovered with an average atomic mass of 245.6 amu.

Hence, the isotope which is most likely to be the most abundant is isotope #2 that has a mass of 244.9 amu because it is closest in mass to the relative atomic mass (weighted average) of 245.6 amu.

262. 5cm3.

using the Boyles law formula. p1v1=p2v2

P1=760torr.

v1=525cm³

p2=760×2=1520torr.

v2=?

p1v1=p2v2

760×525=1520×v2

v2=[ 760×525]÷1520

v2= 262.5cm³

when the pressure increases, the volume decreases.

Answer:

B

Explanation:

took the test

D. It should have a half-life much longer than the age of the object being dated. When using isotopes for dating purposes, it is important to choose an isotope with a half-life that is significantly longer than the age of the object being dated.

The half-life is the time it takes for half of the radioactive isotopes in a sample to decay into stable isotopes. By measuring the ratio of the original radioactive isotope to the decay product, scientists can determine the age of the object.

The majority of the radioactive material would have decayed if the isotope had a half-life substantially less than the age of the artefact, making it challenging to precisely establish the age.

On the other hand, the dating procedure would become more challenging and unpredictable if the isotope in the object being dated (option C) has a half-life that varies over time.

As a result, an isotope with a long half-life offers a stronger basis for precise dating since it enables sufficient radioactive decay to take place, producing quantifiable and trustworthy data.

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Answer:

telophase

Explanation:

Answer:

In cellular respiration, cells use oxygen to release energy stored in glucose.

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Answer:oxygen and sugars

Explanation:

Decreasing vapour pressure for the following compounds is as follow:

CH4

CH3CH-CH3CH2CH3

CH3CH2CH2CH2CH3

CH3CH2CH2OH

Vapour Pressure of the compound:

The pressure characteristic of a pure compound's vapour at any given temperature when it is in equilibrium with its liquid or solid state is known as the vapour pressure. Compound molecules that bond well with one another will have a low vapor pressure (less inclination to escape to the vapor phase), whereas compounds that connect poorly with one another would have a high vapor pressure. Vapor pressure is a measure of a compound's capacity to bond with itself.

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The molar mass of  the compound C₄H₈O₄ is 120 g/mol. Then the number of moles of this compound in 95.12 g is 0.79 moles.

One mole of  every substance contains 6.022 × 10²³ atoms or molecules. This number is called Avogadro number. Thus, one mole of every element contains Avogadro number of atoms.

Similarly one mole of every compound contains Avogadro number of molecules. The mass of one mole of a compound is called its molar mass.

molar mass of C₄H₈O₄ = 120 g/mol (C =12g, O= 16g, H =1 g).

then, number of moles in 95.12 g = given mass/molar mass

no.of moles = 95.12 g /120 g/mol = 0.79 moles.

Therefore, the number of moles of the compound in 95.12 g is 0.79 moles.

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Answer:

4

Explanation:

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K(s) + 2HCl(aq) ----> 2KCl (aq) +H2(g) is an example of single replacement reactions.

A single-displacement reaction, also known as single replacement reaction or exchange reaction, is a chemical reaction in which one element is replaced by another in a compound.

Single-replacement reactions always involve two pure elements and one aqueous compound/solution. In the above reaction, the A and C would be pure elements.

A single replacement reaction, sometimes called a single displacement reaction, is a reaction in which one element is substituted for another element in a compound.

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Answer:

Explanation:

To calculate the molarity of the solution, we first need to determine the mass of calcium chloride (CaCl2) in 100 g of the solution.

If the solution is 22.3% calcium chloride by mass, this means that there are 22.3 g of CaCl2 in 100 g of the solution.

We can use the density of the solution to convert 100 g of the solution to its volume:

volume of 100 g of the solution = mass of the solution / density of the solution

volume of 100 g of the solution = 100 g / 1.20 g/mL = 83.3 mL

Now, we can calculate the molarity of the solution using the following formula:

molarity = moles of solute / volume of solution (in L)

The molar mass of CaCl2 is 40.08 + 2(35.45) = 110.98 g/mol. Therefore, the number of moles of CaCl2 in 22.3 g of the solution is:

moles of CaCl2 = 22.3 g / 110.98 g/mol = 0.2008 mol

The volume of the solution containing 22.3 g of CaCl2 is:

volume of solution = 83.3 mL / 1000 mL/L = 0.0833 L

Substituting these values into the formula for molarity, we get:

molarity = 0.2008 mol / 0.0833 L = 2.41 M

Therefore, the molarity of the aqueous solution that is 22.3% by mass calcium chloride is 2.41 M.