scientists often work on projects for a long time and fail to see sources of error in their research. Which process allows an outside expert to look at the scientist’s project and point to sources of error?

Answer:

The final temperature of the mixture is 44.9°C

Explanation:

Mass of the substance (gold) = 2.575g

Specific heat capacity of gold = 0.129J/g°C

Initial temperature (T1) = 75°C

Final temperature (T2) = ?

Energy lost = 10J

Heat energy(Q) = MC∇T

Q = heat energy (in this case lost)

M = mass of the substance

C = specific heat capacity of the substance

∇T = change in temperature of the substance = (T2 - T1)

Q = MC∇T

Q = MC(T2 - T1)

-10 = 2.575 × 0.129 × (T2 - 75) energy is -ve because it was energy lost.

-10 = 0.3321 × (T2 - 75)

-10 = 0.3321T2 - 24.9075

Collect like terms

0.3321T2 = 24.9075 - 10

0.3321T2 = 14.9075

T2 = 14.9075 / 0.3321

T2 = 44.88

T2 = 44.9°C

The final temperature of the mixture is 44.9°C

Answer:

Explanation:

V1/T1 =V2/T2    at constnant pressure

Answer:

c

Explanation:

Answer: orbitals supernumerary

Explanation:

Answer:

both S orbital and p orbitals

Explanation:

took the exam got the question right.

Answer:

[tex]\large \boxed{\text{-92 $^{\circ}$C}}[/tex]

Explanation:

We can use the Ideal Gas Law and solve for T.

pV = nRT

Data  

p = 1.25 atm

V = 25.0 L

n = 2.10 mol

R = 0.082 06 L·atm·K⁻¹mol⁻¹

Calculations

1. Temperature in kelvins

[tex]\begin{array} {rcl}pV & = & nRT\\\text{1.25 atm} \times \text{25.0 L} & = & \rm\text{2.10 mol} \times 0.08206 \text{ L}\cdot\text{atm}\cdot\text{K}^{-1}\text{mol}^{-1} \times T\\31.25&=&0.09847T\text{ K}^{-1}\\T& = &\dfrac{31.25}{\text{0.098 47 K}^{-1}}\\\\& = &\text{181 K}\end{array}[/tex]

2. Temperature in degrees Celsius

[tex]\begin{array} {rcl}T & = & (181 - 273.15) \, ^{\circ}\text{C}\\& = & -92 \, ^{\circ}\text{C}\\\end{array}\\\text{The temperature of the gas is $\large \boxed{\mathbf{-92 \, ^{\circ}}\textbf{C}}$}[/tex]

Answer:

A) H2O2

Explanation:

Hydrogen peroxide is written as H2O2, which is the chemical formula of the compound, but this can be simplified. Since both H and O have the subscript of 2, they can be simplified to 1, so the empirical formula for H2O2 would be just H and O together (Brainly won't let me say the empirical form because it has the same spelling as a swear word). Thus, the empirical formula and chemical formula are different.

In the case of the other options, they are all in their simplest form and cannot be simplified further, so they are already in their empirical form, so both the chemical form and empirical form are the same.

Answer:

fddff s

Explanation:

v c dggbgzfx

Answer: [tex]1.6\times 10^4[/tex]

Explanation:

Scientific notation is defined as the representation of expressing the numbers that are too big or too small and are represented in the decimal form with one digit before the decimal point times 10 raise to the power.

For example : 5000 is written as [tex]5.0\times 10^3[/tex]

In division , the result would contain the same number of significant digits as there in the least precise number , thus the answer would have 2 significant digits.

[tex]\frac{1.248\times 10^{-2}}{7.8\times 10^{-7}}=1.6\times 10^4[/tex]

Answer:

Therefore, 1.00 mole of the gas is present in the container.

Explanation:

The following data were obtained from the question:

Volume (V) = 22.41L

Temperature (T) = 273K

Pressure (P) = 101.325 kPa

Gas constant (R) = 8.31 L.kPa/mol.K.

Number of mole (n) =...?

The number of mole of the gas in the container can obtained by applying the ideal gas equation as illustrated below:

PV = nRT

Divide both side by RT

n = PV /RT

n =101.325  x 22.41 / 8.31 x 273

n = 1.00 mole.

Therefore, 1.00 mole of the gas is present in the container.

Answer:

1 mole of gas is contained in 22.41 liters at 101.325 kPa and 0ᴼC

Explanation:

Ideal gases are a simplification of real gases that is done to study them more easily. It is considered to be formed by point particles, do not interact with each other and move randomly. It is also considered that the molecules of an ideal gas, in themselves, do not occupy any volume.

The pressure, P, the temperature, T, and the volume, V, of an ideal gas, are related by a simple formula called the ideal gas law:  

P*V = n*R*T

where P is the gas pressure, V is the volume that occupies, T is its temperature, R is the ideal gas constant, and n is the number of moles of the gas.

In this case:

Replacing:

1 atm*22.41 L=n* 0.082 [tex]\frac{atm*L}{mol*K}[/tex]*273 K

Solving:

[tex]n=\frac{1 atm*22.41 L}{0.082\frac{atm*L}{mol*K} *273 K}[/tex]

n=1  mole

1 mole of gas is contained in 22.41 liters at 101.325 kPa and 0ᴼC

Answer:

The total number of molecules in each phase stays constant

Explanation:

i just took the test and got it right.

In the dynamic equilibrium between 2 phases, the total number of molecules in each phase stays constant (Option D).

Dynamic equilibrium occurs when the direct and reverse rates are equal and the concentrations remain constant over time.

Which describes two phases in dynamic equilibrium?

In the dynamic equilibrium between 2 phases, the total number of molecules in each phase stays constant (Option D).

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Some Energy is released into the environment as heat

Explanation:

Answer:

The pressure will increase due ot expnasion of gasses in a closed sealed tube tube .

Explanation:

Answer:

The pressure inside of a sealed tube will increase if the temperature is raised.

Explanation:

When the temperature of the gas inside the sealed tube is raised, the particles within that tube will start to become faster and faster. Because they are going faster they collide with the sides of the tube faster, therefore increasing the pressure inside the sealed tube.

Hope this helps!

Answer:

See the answer below

Explanation:

Aqueous solution of copper II nitrate contains solute of copper II nitrate dissolved in water. The equation for the reaction is as below:

[tex]Cu(NO_3)_2 (s)[/tex] + [tex]H_2O (l)[/tex] --> [tex]Cu(NO_3)_2 (aq)[/tex]

Hence, the solute chemical is copper II nitrate while the solvent is water.

Chemical formula of copper II nitrate - [tex]Cu(NO_3)_2[/tex]

Chemical formula of water - [tex]H_2O[/tex]

Answer: Quartz

Explanation: I looked it up ;)

Answer:

1) Conditions necessary for rusting are:

a) Presence of atmospheric oxygen or air

b)Presence of water or moisture

2) For protecting the iron gate, we can paint it because the paint will coat it and protect it from atmospheric oxygen and water.

3) Magnesium, Carbon and Oxygen (MgCO₃)

Answer:

One of the most common ways of producing UV light is passing an electric current through vaporized mercury or some other gas. This type of lamp is commonly used in tanning booths and for disinfecting surfaces. The lamps are also used in black lights that cause fluorescent paints and dyes to glow.Explanation:

Answer:

5.449 x 10¹⁸ Hz

Explanation:

Energy (E) =Frequency (F) x Plancks constant (h)

F= 3.611x10⁻¹⁵J / 6.626 x 10⁻³⁴ Js⁻¹

F =5.449 x10¹⁸ s⁻¹ or 5.449 x 10¹⁸ Hz

The metallic pan iis most likely going to be used on a stove.

The stove is heating something, and the conductive metallic pan will, well, conduct that heat throughout the entire body of the pan. Doing this will spread the heat to the handle, burning your hands.

Both wood and plastic are insulators, and they do not conduct heat or electricity. They will insulate your hands and protect them from the heat.

Answer:

A lower pH of the mouth creates bad bacteria that eventually lead to decay of the tooth.  

It can be prevented by avoiding food that causes acidity.

Explanation:

Tooth decay is caused by the pH level in the mouth dropping below 5.5, meaning it is acidic. It can be prevented by brushing your teeth as toothpaste is an alkali which will neutralise the pH level in your mouth.

Hope this helps

Answer:

A.) -5448 kJ/mol

Explanation:

I got it correct on founders edtell

Answer:

people are mostly exposed to chemicals through their nose, mouth, eyes, and ears

Explanation:

they are the easiest way for anything, bad or good, to enter the body because  people touch their face alot.

This might not answer what you were looking for but the other answer covered it pretty well so I thought I'd give you another angle to the question!

Hope this helps!!

Answer:

1.24mol

Explanation:

m(MgO)=50g

molar mass=40.30g/mol (i search in google coz dosnt have book)

n=mass/molar mass

=50/40.30

=1.24mol

Answer:

17.1 Liters

Explanation:

It's a gas law question (more specifically a Charles's Law question). Formula is V1/T1 = V2/T2. You're given V1 and T1 and T2. However, in order to use the equation, temperature needs to be in Kelvins (by subtracting the degrees C from 273) for the numbers to work (among other reasons, the 0 degrees C will always give you an answer of zero or undefined). Placing all temps in kelvins makes the answers come out right. So 20L/273K = xL/233K gives you the answer when you cross-multiply.

Considering the Charles's law, a weather balloon calibrated at 0.00 °C to have a volume of 20.0 L has  17.07 L at -40.0 °C, assuming pressure is held constant.

The gas laws are a set of chemical and physical laws that allow determining the behavior of gases in a closed system. The parameters evaluated in these laws are pressure, volume, temperature and moles.

Charles's law is one of the gas laws. It relates the volume and the temperature of a certain quantity of ideal gas, kept at a constant pressure.

This law states that, at constant pressure, the volume of a gas is directly  proportional to its temperature. In other words, for a given sum of gas at constant pressure, as the temperature increases, the volume of the gas increases, and as the temperature decreases, the volume of the gas decreases.

Mathematically, Charles's law says that the quotient that exists between the volume and the temperature will always have the same value:

[tex]\frac{V}{T}=k[/tex]

Being an initial state 1 and a final state 2, it is true:

[tex]\frac{V1}{T1}=\frac{V2}{T2}[/tex]

In this case, you know:

Replacing:

[tex]\frac{20 L}{273 K}=\frac{V2}{233 K}[/tex]

Solving:

[tex]V2=233 K x\frac{20 L}{273 K}[/tex]

V2=17.07 L

Finally, a weather balloon calibrated at 0.00 °C to have a volume of 20.0 L has  17.07 L at -40.0 °C, assuming pressure is held constant.

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Answer:

The answer is protons and nuetrons

Explanation:

Answer:

a) 64.27%

b) 58%

c) ethanol is the limiting reactant

d) ethanol is the limiting reactant

Explanation:

We have to note that the expected yield is the theoretical yield while the actual mass or amount of product formed is the actual yield.

a) theoretical yield=68.3g

Actual yield= 43.9 g

Percentage yield= 43.9/68.3 ×100

Percentage yield= 64.27%

b) theoretical yield= 0.0722 moles

Actual yield = 0.0419

Percentage yield= 0.0419/0.0722 × 100

Percentage yield= 58%

c) note that the limiting reactant yields the least number of moles of product

Ethanol will be the limiting reactant since it is not present in excess.

d) from the reaction equation;

1 mole of acetic acid produces 1 mole of ethyl acetate

0.58 moles of ethanol produces 0.58 moles of ethyl acetate

1 mole of acetic acid yields 1 mole of ethyl acetate

Hence 0.82 moles of acetic acid yields 0.82 moles of ethyl acetate

Hence ethanol is the limiting reactant.

Answer:

49 g/L is the concentration of the acid

Explanation:

Firstly, we proceed to write the equation of reaction.

2NaOH + H2SO4 ——-> Na2SO4 + 2H2O

We can see that 1 mole of the base reacted with two moles of the acid.

kindly note that dm^3 is same as liter

Firstly, we need to get the concentration of the reacted sulphuric acid in g/L

we use the simple titration equation below;

CaVa/CbVb = Na/Nb

From the question;

Ca = ?

Va = 25 cm^3

Cb = 20 g/L

we convert this to concentration in mol/L

Mathematically, that is concentration in g/L divided by molar mass in g/mole

molar mass of NaOH = 40 g/mol

so we have; 20g/L / 40 = 0.5 mol/L

Vb = 50 cm^3

Na = 1

Nb = 2

Where C represents concentrations, V volumes and N , number of moles

Now, substitute the values;

Ca * 25/0.5 * 50 = 1/2

25Ca/25 = 0.5

So Ca = 0.5 mol/L

Now to get the concentration of H2SO4 in g/L

What we do is to multiply the concentration in mol/L by molar mass in g/mol

That would be 0.5 * 98 = 49 g/L

The concentration of the acid in grams per litre is 49g/L

From the question,

We are to determine concentration of the sodium hydroxide solution.

First, we will write a balanced chemical equation for the reaction.

The balanced chemical equation for the reaction is

2NaOH + H₂SO₄ → Na₂SO₄ + 2H₂O

This means,

2 moles of NaOH is required to completely neutralize 1 mole of H₂SO₄

From the formula

[tex]\frac{C_{A}V_{A} }{C_{B}V_{B} }=\frac{n_{A} }{n_{B} }[/tex]

Where

[tex]C_{A}[/tex] is the concentration of acid

[tex]C_{B}[/tex] is the concentration of base

[tex]V_{A}[/tex] is the volume of acid

[tex]V_{B}[/tex] is the volume of base

[tex]n_{A}[/tex] is the mole ratio of acid

[tex]n_{B}[/tex] is the mole ratio of base

From the question

[tex]V_{A}= 25 \ cm^{3}[/tex]

[tex]C_{B} = 20 \ g/dm^{3}[/tex]

Convert this to mol/dm³

Molar mass of NaOH = 40 g/mol

Using the formula

[tex]Concentration\ in \ mol/dm^{3} =\frac{Concentration\ in \ g/dm^{3}}{Molar\ mass}[/tex]

∴ Concentration of the NaOH in mol/dm³ = [tex]\frac{20}{40}[/tex]

Concentration of the NaOH in mol/dm³ = 0.5 mol/dm³

∴ [tex]C_{B} = 0.5 \ mol/dm^{3}[/tex]

and

[tex]V_{B} = 50 \ cm^{3}[/tex]

From the balanced chemical equation

[tex]n_{A} = 1[/tex]

[tex]n_{B} = 2[/tex]

Putting the parameters into the formula, we get

[tex]\frac{C_{A} \times 25}{0.5 \times 50}= \frac{1}{2}[/tex]

Now, this becomes

[tex]2 \times 25 \times C_{A}=0.5 \times 50 \times 1[/tex]

Then, we get

[tex]50 C_{A} = 25[/tex]

∴ [tex]C_{A} = \frac{25}{50}[/tex]

[tex]C_{A} = 0.5 \ mol/dm^{3} = 0.5 \ mol/L[/tex]

Now, we will determine the concentration in g/L

From the formula,

Concentration in g/L = Concentration in mol/L × Molar mass

From the question,

Molar mass of sulfuric acid = 98

∴ Concentration of the acid in g/L = 0.5 × 98

Concentration of the acid in g/L = 49 g/L

Hence, the concentration of the acid in grams per litre is 49g/L

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Answer:

The molar concentration of the final solution is 1.71 [tex]\frac{moles}{liter}[/tex]

Explanation:

Molarity is a way of expressing the concentration of solutions and indicates the number of moles of solute dissolved per liter of solution.

The molarity of a solution is calculated by dividing the moles of the solute by the volume of the solution.:

[tex]Molarity (M)=\frac{number of moles of solute}{volume}[/tex]

Molarity is expressed in units ([tex]\frac{moles}{liter}[/tex]).

Then, the number of moles of solute can be calculated as:

number of moles of solute= molarity* volume

So, in this case, the final concentration can be calculated as:

[tex]Final molarity (M)=\frac{Total number of moles of solute}{Total volume}[/tex]

where, being 65 mL=0.065 L, 125 mL=0.125 L and 190 mL=0.190 L (because 1000 mL= 1 L):

Replacing:

[tex]Final molarity (M)=\frac{0.324595 moles}{0.190 L}[/tex]

Final molarity ≅ 1.71 [tex]\frac{moles}{liter}[/tex]

The molar concentration of the final solution is 1.71 [tex]\frac{moles}{liter}[/tex]

The spin of electrons is reversed. Hence, option D is correct.

Enthalpy is the sum of the internal energy. and pressure times volume.

During a reaction, the enthalpy of the reactants and the products are not equal which means the spin of electrons is reversed.

Hence, option D is correct.

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Answer:

The answer is Observation 1 is a result of copper atoms losing two electrons.

Explanation:

The electrons result in the color change of the copper strip, causing the gray particles to join onto the metal.

Answer:

C

Explanation:

Observation 1 is a result of the copper atoms losing two electrons. It came out as the right answer.