A student estimates that 27 students will attend this month's
Science Club meeting 34 students attend. What was the
student's percent error?

The original pH of the gastric juice sample is 3.43

pH serves as a measure to calculate the acidity/alkalinity of a solution. It's ranges is between 0 - 14, with 7 being neutral. A pH below 7 indicates acidity and a pH above 7 indicates basicity. pH is actually a measure of the relative amounts of free hydrogen and hydroxyl ions in water.

As we know:

M₁V₁ = M₂V₂

For the given question:

M₁ = Concentration of gastric juice

V₁ = Volume of gastric juice (20 ml)

M₂ =  Concentration of NaOH (0.0011 M)

V₂ = Volume of NaOH (6.7 ml)

So, M₁ = M₂V₂ / V₁

M₁ = 0.0011 × 6.7/20

M₁ = 0.000365

For pH:

pH = -log [H⁺]

pH = -log [0.000365]

pH = 3.43

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Answer: \(1.25dm^3\) of unreacted oxygen is left.

Explanation:

To calculate the moles :

\(\text{Moles of solute}=\frac{\text{given volume}}{\text{Molar Volume}}\)    

\(\text{Moles of} CO_2=\frac{3.60dm^3}{22.4dm^3}=0.161moles\)

\(\text{Moles of} O_2=\frac{7.25dm^3}{22.4dm^3}=0.324moles\)

\(C_3H_8(g)+5O_2(g)\rightarrow 3CO_2(g)+4H_2O(l)\)  

According to stoichiometry :

3 moles of \(CO_2\)  = 5 moles of \(O_2\)  

Thus 0.161 moles of \(CO_2\) =\(\frac{5}{3}\times 0.161=0.268moles\)  of \(O_2\)

moles of \(O_2\)  left unreacted = (0.324-0.268) = 0.056

Volume of \(O_2\) left unreacted = \(moles\times {\text {Molar volume}}=0.056mol\times 22.4dm^3/mol=1.25dm^3\)

Thus \(1.25dm^3\) of unreacted oxygen is left.

When electricity is passed through sodium sulfate solution, it separates the water molecules. Oxygen gas is produced at one electrode called the anode. At the other electrode called the cathode, hydrogen gas is produced. So, during electrolysis, oxygen gas is made at the anode and hydrogen gas is made at the cathode.

The mass percent concentration of the obtained ammonia solution is approximately 0.00833%.

To determine the mass percent concentration of an ammonia solution, we need to know the mass of ammonia present in the solution and the total mass of the solution.

In this case, we are given that 11.2 dm3 of NH3 gas, as measured in normal conditions (which is equivalent to 0.0112 m3), were dissolved in 100 cm3 of water. To calculate the mass of ammonia present in the solution, we first need to calculate the number of moles of NH3 using the ideal gas law, PV = nRT, where P is the pressure, V is the volume, n is the number of moles, R is the gas constant, and T is the temperature.

Assuming standard temperature and pressure (STP), we can use a pressure of 1 atm and a temperature of 273 K, giving us:

\($n = \frac{PV}{RT}\)

\(= \frac{(1 \text{ atm} * 0.0112 \text{ m}^3)}{(0.08206 \text{ L atm/mol K} * 273 \text{ K})} = 0.000489 \text{ mol}$\)

The molar mass of NH3 is 17.03 g/mol, so the mass of NH3 present in the solution is:

mass NH3 = n * molar mass

= 0.000489 mol * 17.03 g/mol

= 0.00833 g

To calculate the mass percent concentration, we divide the mass of NH3 by the total mass of the solution (which is the mass of NH3 plus the mass of water):

mass percent concentration = \(\frac{mass,NH_3}{total,mass} \times 100%$\)

The mass of water is equal to its volume times its density, which is approximately 1 g/cm3:

mass water = \(100\text{ cm}^3 * 1\text{ g/cm}^3 = 100\text{ g}$\)

Therefore, the total mass of the solution is:

total mass = mass NH3 + mass water = 0.00833 g + 100 g = 100.00833 g

Substituting these values, we get:

mass percent concentration = \(\frac{0.00833 \text{ g}}{100.00833 \text{ g}} \times 100%\)

= 0.00833%

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Answer: Mechanical: Mechanical energy is the ability to do work.

Thermal: Thermal energy refers to the energy contained within a system that is responsible for its temperature.

Chemical:  Energy stored in the bonds of chemical compounds. Chemical energy may be released during a chemical reaction, often in the form of heat.

Electromagnetic: Electromagnetic energy is a form of energy that is reflected or emitted from objects in the form of electrical and magnetic waves that can travel through space.

Electrical: Electrical energy is the power an atom's charged particles have to cause an action or move an object.

Nuclear: Nuclear energy is the energy in the nucleus, or core, of an atom.

Answer:

D atom

Explanation:

Answer:

the sun Solar energy

Explanation:

Energy from the sun. Solar energy is the original source of most energy on Earth. There are many ways we use energy from the Sun.

Answer:

the sun Solar energy

Explanation:

Energy from the sun. Solar energy is the original source of most energy on Earth. There are many ways we use energy from the Sun. btw hope this helps u out =)

Answer:

hope this document helps! it's kinda hard to type out the explanation but ill try

Explanation:

divide the percenatge by the molar mass of the element.

(do this for both elements) \

find the lowest number and divide the results with it

now you have your empirical formula (with the rounded answers)

then find the molar mass of your empirical formula

divide the number given (267) by the molar mass to get a rounded number.

multiply that rounded answer to your empirical formula to get your empirical formula. :)

Answer:

it decrease when a solution becomes more acidic which means that decrease in pH means increase..

Answer:

it's ph decreases.. meaning those with a small ph value are more acidic.forinstance one with a ph of 1 is more acidic than the one with a ph of 3.

I hope this helps

When ammonia (NH3) is dissolved in a solution, it accepts hydrogen ions from its surroundings. Ammonia is therefore a weak-base.

Bases are a class of compounds that accept hydrogen ions (protons) from acids to generate solutions. They are the opposites of acids in that they dissolve in water to form solutions that have a pH greater than 7.0.Bases react with acids to produce salts and water through a process known as neutralization. When a base absorbs a hydrogen ion from an acid, the acid loses its hydrogen ion. Ammonia is one of the most common weak bases. It is used as a cleaner, refrigerant, and as a building block for fertilizers, among other things.

Therefore,When ammonia (NH3) is dissolved in a solution, it accepts hydrogen ions from its surroundings. Ammonia is therefore a weak-base.

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Answer:

B and C

Explanation:

ClO3-: The chlorine atom carries a single negative charge.

ClO4-: The chlorine atom carries a single negative charge.

NO3-:The nitrogen atom does not carry any charge, and the molecule as a whole carries a single negative charge.

Certainly! Here are the drawings of the molecules you requested:

1. ClO3-

   O

    |

Cl - O

    |

   O [-

2. ClO4-

   O

    |

Cl - O

    |

   O

    |

   O [-

3. NO3-

   O

    ||

N - O

    |

   O [-

4. SO3

 O

 ||

S - O

 ||

 O

Please note that for SO3, it does not carry any charge (neutral molecule), as requested.

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Answer:

Explanation:

1. It is five valence electrons.

2. It is four valence electrons.

3. It is six valence electrons.

4. It is two valence electrons.

I do hope I helped you! :)

Answer:

1. c

2. b

3. a

4.d

Explanation:

The percent Theoretical yield of Al(OH)3 is 84.1%.

(a) Limiting Reagent The limiting reagent is a reactant that is completely consumed in a chemical reaction, restricting the amount of product that can be produced from other reactants. To identify the limiting reagent:

Use the given masses of both reactants to calculate the number of moles of each reactant by dividing the mass by its respective molar mass.KOH (potassium hydroxide) number of moles

= Mass/Molar mass

= 7.50 g/56.11 g/mol = 0.1335 molAlCl3 (aluminum chloride) number of moles

= Mass/Molar mass = 7.50 g/133.34 g/mol

= 0.05625 mol

Now, use the stoichiometry coefficients in the balanced equation to determine which reactant limits the amount of product formed.The balanced equation:

3 KOH (aq) + AlCl3 (ag) → 3 KCl (aq) + Al(OH)3 (s)

From the balanced equation, 3 moles of KOH react with 1 mole of AlCl3.

To find the number of moles of AlCl3 that are needed to react with the 0.1335 moles of KOH, multiply 0.1335 moles by the ratio of 1 mole AlCl3 to 3 moles KOH.

This gives the number of moles of AlCl3 needed to react completely with KOH.

The amount of AlCl3 available is 0.05625 moles.0.1335 moles KOH x 1 mol AlCl3 / 3 mol KOH = 0.0445 moles

AlCl3Hence, AlCl3 is the limiting reagent.

(b) Theoretical YieldNow that we know AlCl3 is the limiting reagent, we can use it to calculate the theoretical yield of Al(OH)3.

The theoretical yield is the amount of product that would be produced if all the limiting reactant were converted into product. First, calculate the number of moles of Al(OH)3 formed using the balanced chemical equation.1 mole of AlCl3 reacts with 1 mole of Al(OH)3.0.0445 moles of AlCl3 would react with 0.0445 moles of Al(OH)3.

Number of moles of Al(OH)3 produced

= 0.0445 moles

To convert the number of moles to grams, use the molar mass of Al(OH)3.

Mass = Number of moles x Molar mass

= 0.0445 mol x 78.00 g/mol

= 3.47 gAl(OH)3 (Theoretical Yield)

Percent Yield% Yield = (Actual Yield/Theoretical Yield) x 100Substituting the given values,

Actual yield = 2.92 g

Theoretical yield = 3.47 g%

Yield = (2.92 g/3.47 g) x 100%

Yield = 84.1%.

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Explanation:

To solve this question, we need to use the Hess's Law.

Hess's Law states that: in a chemical reaction, the heat released or absorbed is constant and independent of the number of steps the reaction goes through. That is, the law states that the enthalpy change of a chemical reaction depends only on its initial state and its final state.

Hess's Law is also known as the law of the sum of heats of reaction, because the enthalpy change is equal to the sum of the changes in the steps through which the chemical reaction passes (intermediate reactions). The calculation is performed as follows:

- If the chemical reaction is inverted, the sign of the enthalpy change must also be inverted;

- If the equation is multiplied, the enthalpy change must also be multiplied;

- If dividing the equation, the enthalpy change must also be divided.

So we're going to invert, divide, or multiply each given equation in order to get the equation that the question gives us.

The equation the question gives us is:

4Al(s) + 3MnO2(s) --> 2Al2O3 (s) + 3Mn(s)

Let's multiply the first equation by 2:

4 Al + 3 O2 --> 2 Al2O3

ΔH = -1676 * 2 = -3,352 kJ

Let's invert and multiply by 3 the second equation:

3 MnO2 -> 3 Mn + 3O2

ΔH = -521 * 3 * (-1)

ΔH = 1,563 kJ

Answer: -1,789 kJ

The number of liters of carbon dioxide measured at STP that could be produced from 6.71 g of propane is 15.5 L.

When propane (C3H8) is burned completely with oxygen (O2), it produces carbon dioxide (CO2) and water vapor (H2O). The balanced chemical equation for the reaction is: C3H8 + 5O2 → 3CO2 + 4H2O
From the balanced equation, we can see that 1 mole reacts with 5 moles of oxygen to produce 3 moles of carbon dioxide. Its molar mass is 44.1 g/mol, so 6.71 g of propane is equivalent to 0.152 moles. Therefore, the amount of carbon dioxide produced would be 0.456 moles (3 moles CO2 per 1 mole C3H8). At STP (standard temperature and pressure), 1 mole of any gas occupies 22.4 L of volume. Therefore, the volume of carbon dioxide produced at STP would be:
V = nRT/P = (0.456 mol) (0.0821 L·atm/mol·K) (273 K) / (1 atm) = 15.5 L
Thus, the number of liters of carbon dioxide measured at STP that could be produced from 6.71 g of propane is 15.5 L.

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Answer:

particulates and gases

Explanation:

Answer:

Explanation:

1 = A

Sublimation is the process where by a sample is heated to pass through solid phase to gaseous phase without the intermittent liquid phase. Example of substance that sublime is camphor.

2 = D

Decantantion

5 = F

Filtration is the process a liquid from solid using a porous material. This technique requires a set up and a good porous material eg filter paper.

6 = B

This technique is to separate a mixture of solids by converting them from solid phase to gaseous phase since they sublime.

3 = deposition.

The answer isn't in the option but deposition is the process of substance in gaseous phase to change into solid state without passing through liquid phase. Deposition is the opposite of sublimation.

4 = E

Hydration is a specific example of the phenomenon known generally as a. solvation

The act of hydrating involves combining or dissolving an object in water. It is a particular instance of the more general phenomena known as solvation, which is the process by which solvent molecules surround and scatter a solute to create a homogeneous solution. However, hydration explicitly refers to solvation with water as the solvent.

Solvation may also happen with solvents other than water. Solvation is the process through which a solute and solvent interact to stabilise a solute species. Due to its impact on the solubility, reactivity, and behaviour of compounds in solution, solvation is a crucial mechanism in many chemical and biological processes.

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A student investigated the electrolysis of aqueous solutions using inert electrodes. The element graphite is a form of electrode. The correct option is C.

The process of separating water into hydrogen and oxygen is known as electrolysis. This reaction occurs in a device known as an electrolyzer.

Because of the structure of graphite, which makes it a great conductor, graphite rods are employed as electrodes in electrolysis. There are anodes and cathodes in the electrolysis process.

Therefore, the correct option is C. Electrodes.

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Answer:

because it is a sign that there are more producers for the consumers.

Explanation:

An ecosystem consist of the abiotic or inorganic components, the animals[consumers], the plants[producers] and the decomposers. An ecosystem simply means the environment of organisms that are living together and the way these organisms interact with another.

The producers that is the plants are the ones manufacturing food by themselves either by photosynthesis or chemosynthesis and the consumers are the ones relying on the producers for food.

The ecosystem is still healthy even when there's still a lot of consumers in it because it shows that there are come producers that is to say the producers are more also. If this is not the case, then the ecosystem will not be healthy as the consumers will eat the producers until the producers will not be enough.

Carbon plays a fundamental role in the structure of organic compounds.

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Answer:

The substance is a mixture because it left a white powder in the beaker when boiled.

Explanation:

On the basis of the evidence collected, it can be concluded that unknown liquid substance is a compound as it left behind a residue in the beaker on decomposition.

Compound is defined as a chemical substance made up of identical molecules containing atoms from more than one type of chemical element.

Molecule consisting atoms of only one element is not called compound.It is transformed into new substances during chemical reactions. There are four major types of compounds depending on chemical bonding present in them.They are:

1)Molecular compounds where in atoms are joined by covalent bonds.

2) ionic compounds where atoms are joined by ionic bond.

3)Inter-metallic compounds where atoms are held by metallic bonds

4) co-ordination complexes where atoms are held by co-ordinate bonds.

They have a unique chemical structure held together by chemical bonds Compounds have different properties as those of elements because when a compound is formed the properties of the substance are totally altered.

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potassium-42 has a half-life of 12.4 hours. approximately how much of an 1202 mg sample of potassium-42 will be left after 2 days is 1522 mg.

a potassium isotope with a half-life of 12.36 hours that is synthesised artificially and is employed as a radioactive tracer in research on how much potassium is distributed in physiological fluids.

The time needed for a reactant's concentration to drop to half its initial value is a different method of describing reaction rates. The reaction's half-life, denoted by the symbol t1/2, is the duration of this time. Therefore, the reactant concentration must fall from [A]0 to [A]0/2 over the course of a reaction's half-life. The quicker reaction will have a shorter half-life if two reactions have the same order, while the slower reaction will have a longer half-life.

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If someone who look up to does anything that makes you want to do something, this is known as direct pressure directly from the other person's mouth. The plan you use to accomplish the goal it your activity.

The Standard unit for pressures seems to be the pascal (Pa), which is equal to one newton / square meter (N/m2) of pressure is defined of surface. An object's pressure is inversely related to its force and proportional to both

Pressure is created by molecules moving quickly and crashing into the container's walls. The quantity and intensity of molecular collisions in a given region determine the pressure there.

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1. Sodium triphosphate ·

2. Sodium hydroxide ·

3. potassium hydroxide

4. Sodium Lauryl Sulfate · 5.Hydroxyethylcellulose ·

6. Sodium carbonate

Answer:

c

Explanation:

took the exam