we ignored the heat lost to the styrofoam cup and the air in the claculations for this lab. did this cause your claculated values for enthalpy to be too large or too small

A mixture has a mas of 450 grams. Of that mixture,35 grams is sulfur . Therefore, 11% is the percentage of sulfur in the mixture.

The mass percent equation is defined as the mass of each element in one mole of the compound, as well as the molar mass. With these masses, you can calculate each element's mass proportion.

In order to represent the mass percent of a solution, the kilograms of solute are divided by the kilograms of solution, and the result is multiplied by 100.

percentage of sulfur = mass of sulfur/ mass of mixture×100

mass of sulfur= 5 grams

mass of mixture =450 grams

substituting all the given values in the above equation, we get

percentage of sulfur = 5 / 450=0.011×100= 11%

Therefore,  11% is the percentage of sulfur in the mixture.

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Answer:

C: the repulsion of electrons and electrons.

Explanation:

According to the VSEPR theory, molecular shapes adjust so that the electrons can be as far apart as possible due to electrons repelling each other, which would mean the only possible answer is C.

Answer:

Structure of boron trifluoride, an example of a molecule with trigonal planar geometry.

Explanation:

Angiotensin -I (A-I) is a peptide hormone that is produced from the proteolytic action of renin on angiotensinogen. In order for A-I to become its active form, angiotensin -II (A-II), it must be subjected to the action of an enzyme known as angiotensin -converting enzyme (ACE).

Correct option is A.

ACE is a dipeptidyl carboxypeptidase that cleaves the terminal dipeptide from A-I, leaving the active form of A-II. This process is important because A-II is a potent vasoconstrictor that also stimulates aldosterone secretion from the adrenal cortex.

Aldosterone helps to regulate sodium and water balance in the body, and thus A-II plays a key role in maintaining normal blood pressure and fluid balance in the body. Therefore, ACE is necessary for the transformation of A-I into A-II, and without it the body would be unable to produce the active form of the hormone.

Correct option is A.

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Yes, the molecular polarity changes from polar to nonpolar when SO3 obtains two electrons because it modifies the molecule form around S.

Nonpolar compounds are said to be symmetric, which means that all of the sides surrounding the core atom are the same and bound to the same element without any unshared pairs of electrons.

A polar molecule has an asymmetrical configuration.

When the bound atoms have different electronegativities, polar molecules are produced.

If the arrangement is symmetrical and the arrows are all the same length, the molecule is nonpolar. If the arrows' lengths are different and they do not balance one another, the molecule is polar.

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The correct option is 1.CH3CH2S

The conjugate base of CH3CH2SH (ethanethiol) is CH3CH2S-.

To determine the conjugate base, we remove a proton (H+) from the molecule. In this case, removing a proton from the sulfur atom (S) results in the formation of the ethanethiolate ion (CH3CH2S-).

The remaining options given are:

CH3CH2S-: This is the correct conjugate base of ethanethiol.

CH3CH2-: This is not the conjugate base of ethanethiol, as it is missing the sulfur atom.

CH3CH2SH2: This is not the conjugate base of ethanethiol, as it retains the proton on the sulfur atom.

CH3CH2S2-: This is not the conjugate base of ethanethiol, as it contains two sulfur atoms (disulfide ion).

None of these: This is not the correct answer since option 1 (CH3CH2S-) is indeed the conjugate base of ethanethiol.

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Answer:

Option (3) 334J.

Explanation:

The following data were obtained from the question:

Mass (m) = 1g

Heat of fusion (ΔHf) = 334J/g

Heat (Q) =?

The heat released can be obtained as follow:

Q = m·ΔHf

Q = 1 x 334

Q = 334J.

Therefore, the heat released when 1g is converted to ice is 334J.

The enthalpy change, ΔH for the chemical reaction, given that 75 grams of chocolate cake are combusted in the calorimeter is 466.9 KJ/mol

First, we shall determine the mole of 75 g of glucose, C₆H₁₂O₆. Details below:

Mole = mass / molar mass

Mole of C₆H₁₂O₆ = 75 / 180

Mole of C₆H₁₂O₆ = 0.417 mole

Next, we shall determine the heat absorbed by water. Details below:

Q = MCΔT

Q = 660 × 4.184 × 70.5

Q = 194681.52 J

Finally, we shall determine the enthalpy change, ΔH, of the reaction. Details below:

Heat absorbed (Q) = 194681.52 J = 194681.52 / 1000 = 194.68152 KJ

Mole of C₆H₁₂O₆ = 0.417 mole

Enthalpy change (ΔH) =?

Q = n × ΔH

194.68152 = 0.417 × ΔH

Divide both sides by 0.417

ΔH = 194.68152 / 0.417

Enthalpy change (ΔH) = 466.9 KJ/mol

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Answer:

coefficient green : 2.4865

exponent (yellow) : 16

Explanation:

Answer:

hi

Explanation:

The compound in medicines should be non polar. Therefore scientists need to be sure of using compounds that are non polar in nature so they pass through the cell membrane and enter into the blood circulation of the body and perform its due function.

The pH of a buffer solution that is 0.15 M chloroacetic acid (C2H3ClO2) and 0.10 M sodium

chloroacetate is 2.7.

Buffer Solution is defined as a water solvent based solution that is mostly consists of a mixture having weak acid and conjugate base of the weak acid, or in other word solution of a weak base and conjugate acid of the weak base.

The buffer solution always acidic or basic.

[H+] = Ka × [weak acid] / [salt] × valancy

[salt] = 0.10M

[weak acid] = 0.15M

Ka = 1.3 x 10-3

[H+] = 1.3 x 10-3 × 0.15/ 0.10

= 0.00195M

Now, as we know that

pH = -log[H+]

= -log(0.00195M)

= 2.7

Thus, we concluded that the pH of a buffer solution that is 0.15 M chloroacetic acid (C2H3ClO2) and 0.10 M sodium

chloroacetate is 2.7.

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False. A closed system permits mass exchange with the environment but not energy.

The mass of a something is the total amount of stuff or materials that make it up. The kilogram, or kg, is the symbol for the measurement units. It's important to remember that mass is distinct from gravity. Mass never changes, whereas weight fluctuates as the center of gravity shifts.

Knowing an object's mass is essential since it allows you to determine that however much power will be needed to move it. It is common practice to calculate the mass of an unspecified object using recognized units of weight such milligrams, grams, and kilograms. Anything with both mass and quantity is considered to be matter.

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The number of half-lives that have elapsed since the mineral contained 100% parent atoms would be between 1 and 2 half-lives.

Assuming that the parent isotope decays into the daughter isotope through a process of radioactive decay with a constant half-life, we can use the fact that the proportion of parent to daughter isotopes changes over time in a predictable way to determine how many half-lives have elapsed since the mineral contained 100% parent atoms.

At the start, the mineral contained 100% parent atoms, so we can represent this as a ratio of 1:0 parent to daughter isotopes.

After one half-life, half of the parent isotopes will have decayed into daughter isotopes, and the proportion of parent to daughter isotopes will be 1:1.

After two half-lives, half of the remaining parent isotopes will have decayed into daughter isotopes, and the proportion of parent to daughter isotopes will be 1:3 (one parent isotope for every three daughter isotopes).

After three half-lives, half of the remaining parent isotopes will have decayed into daughter isotopes, and the proportion of parent to daughter isotopes will be 1:7 (one parent isotope for every seven daughter isotopes).

Since the current proportion of parent to daughter isotopes in the mineral is 40% parent and 60% daughter, we can express this as a ratio of 2:3 parent to daughter isotopes.

Comparing this to the ratios we calculated above, we can see that the current ratio of 2:3 is closest to the ratio of 1:3 that occurs after two half-lives. Therefore, we can conclude that between 1 and 2 half-lives have elapsed since the mineral contained 100% parent atoms.

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The D45G variant of GalK has a lower affinity for all three substrates (D-galactose, D-xylose, and L-arabinose) than the wild-type GalK.

The D45G mutation in GalK changes the amino acid at position 45 from aspartic acid (D) to glycine (G). Aspartic acid is a negatively charged amino acid, while glycine is a neutral amino acid. This change in charge affects the polarity of the active site, making it less polar. The substrates for GalK are all polar molecules, so the less polar active site in the D45G variant has a lower affinity for these substrates.

In addition to the change in polarity, the D45G mutation also changes the shape of the active site. The side chain of aspartic acid is bulky, and it helps to fill in some of the gaps in the active site. The side chain of glycine is smaller, so it leaves more gaps in the active site. These gaps make it more difficult for the substrates to bind to the active site.

The combination of these two factors, the change in polarity and the change in shape, results in a lower affinity for all three substrates in the D45G variant of GalK.

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The balanced chemical equation for the reaction in which solid copper(II) hydroxide (Cu(OH)2) is heated to form copper(II) oxide (CuO) and water (H2O) is 2Cu(OH)2 (s) → CuO (s) + H2O (g). Two moles of copper(II) hydroxide decompose to yield one mole of copper(II) oxide and one mole of water vapor. The coefficients in the balanced equation ensure the conservation of atoms during the reaction.

When solid copper(II) hydroxide is heated, it undergoes thermal decomposition, resulting in the formation of copper(II) oxide and water. The chemical formula of copper(II) hydroxide is Cu(OH)2. To balance the equation, we need to ensure that the number of atoms of each element is the same on both sides of the equation.

The balanced equation for the reaction is 2Cu(OH)2 (s) → CuO (s) + H2O (g). This equation indicates that two moles of copper(II) hydroxide decompose to produce one mole of copper(II) oxide and one mole of water vapor. The coefficients 2, 1, and 1 before the formulas of the compounds represent the stoichiometric ratios required for balancing the equation.

Balancing the equation is essential to ensure that the law of conservation of mass is obeyed, meaning that the total number of atoms of each element remains constant throughout the reaction.

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The space left by the free electron in an atom after it has lost one electron is known as a hole.

The term "free electron" refers to an electron that has broken loose from its "parent" atom and is now free to move about the material at random. A vacancy, also known as a hole, is created in the atom when a bonded electron in a lattice atom breaks free. The number of electrons in an atom's valence shell, or n shell in this example, has a significant impact on the electrical properties of the element that the atom represents. The least force of attraction is felt by the electrons in the valence shell since they are the furthest from their nucleus.

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Answer:Explanation:

The Roman numeral must have the same value as the charge of the ion. In our example, the transition metal ion Fe2+ would have the name iron(II). Add the name of the anion to the transition metal ion. In our example, FeCl2 would have the name iron(II) chloride since the anion is Cl-, which has the name chloride.

Answer:

Explanation:

Formula

The current = charge / time

The charge is in coulombs

The time has to be in seconds.

1 minute = 60 seconds

2 minutes = 120 seconds.

charge = 180 coulombs

current = 180 / 120

current = 1.5 amperes.

The percent yield for this reaction is 81.9%.

To calculate the percent yield, we need to use the following formula:
Percent yield = (actual yield / theoretical yield) x 100
We are given that the theoretical yield is 24.9 g and the actual yield is 20.4 g. Plugging these values into the formula, we get:
Percent yield = (20.4 / 24.9) x 100
Percent yield = 81.9%
It is important to note that the percent yield is a measure of the efficiency of a reaction. A high percent yield indicates that a large percentage of the reactants were converted into products, whereas a low percent yield suggests that some of the reactants were lost or that side reactions occurred. In this case, a percent yield of 81.9% indicates that the reaction was fairly efficient and that most of the reactants were converted into products. However, it is still important to consider why the actual yield was lower than the theoretical yield and to optimize the reaction conditions to improve the yield in future experiments.

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Answer: write the solubility equilibrium and the solubility-product constant expression for the slightly soluble salt CaF2 CaF2 (s) <---> Ca2+ (aq) + 2F- (aq) Ksp=[Ca2+][F-]2.

Explanation:

Answer:

mole

Explanation:

is a unit of amount of substance in the International System of Units, defined (since 2019) by fixing the Avogadro constant at the given value. Sometimes, the amount of substance is referred to as the chemical amount

Answer:

197.98g

Explanation:

This question can be calculated using the formula: Q = mcΔT

Where Q= heat transfer

M= mass

C= specific capacity

ΔT= change in temperature

Heat from the copper metal is lost to the water when placed in it, hence, we have:

Q(water) = -Q(copper)

The final temperature of the water is equally to the final temperature of the copper= 22.87°C.

Hence, mcΔT (water) = (-) mcΔT (copper)

Note that, specific heat (C) of water and copper are 4.184 J/g°C and 0.385 J/g°C respectively.

Therefore;

= (m) (4.184) (22.87-21.65) = - {(35.41) (0.385) (22.87-97)}

= m × 4.184 × 1.22 = - {35.41 × 0.385 × -74.13)}

5.10448m = - {-1010.6031}

5.10448m = 1010.6031

m = 1010.6031 ÷ 5.10448

m = 197.98

Therefore, the mass of water copper was added to is 197.98g

The value of Gibbs free energy is 143876.5 joules

The maximum amount of work that can be accomplished by a thermodynamically closed system at constant temperature and pressure can be calculated using the Gibbs free energy (also known as Gibbs energy; symbol: Δ G). Additionally, it offers a prerequisite for any processes like chemical reactions that might take place in such circumstances.

The maximum amount of non-expansion work that can be taken from a closed system (one that may exchange heat and work with its surroundings but not matter) at fixed temperature and pressure is known as the Gibbs free energy change (ΔG =ΔH - TΔS), measured in joules in SI. This maximum is only possible with a fully reversible method. Under these circumstances, when a system changes reversibly from an initial state to a final state, the reduction in Gibbs free energy is equal to the work performed by the system on its surroundings less the work of the pressure forces.

ΔH=-158 kj = enthalpy change

T=655k = temperature

ΔS=-219.9 j/k = entropy

ΔG =ΔH - TΔS

     =-158 -(655 x -219.9)

    = -158 -(-144034.5)

    =143876.5 joules

so, the value of Gibbs free energy is 143876.5 joules

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In phosphoglycerides, fatty acids are esterified at glycerol carbons 1 and 2.

What are phosphoglycerides?

Phosphoglycerides are the most abundant phospholipids in biological membranes, and they are synthesized in the smooth endoplasmic reticulum (SER) of eukaryotic cells.

The class of glycerophospholipids known as phosphoglycerides is distinguished by the presence of a phosphate group in addition to two fatty acids that have been esterified to the first and second carbons of glycerol.

The chain length of fatty acids may change depending on the species or kind of cell they are found in, and they can either be saturated or unsaturated.

Phospholipids that are derived from glycerol are referred to as phosphoglycerides or glycerophospholipids. They make up the bulk of the material that makes up biological membranes.

There are known to be two primary classes, one each for bacteria and eukaryotes, and a third, distinct family for archaea.

Phosphoglycerides, also known as phospholipids, are the principal constituents of biological membranes, such as the plasma membrane of cells.

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Answer:

About 27 mL of water.

Explanation:

We can use the heat transfer equation. Recall that:

\(\displaystyle q = mC\Delta T\)

Heat is transferred from the water with higher temperature to the water with lower temperature. Hence:

\(\displaystyle -q_1 = q_2\)

Substituting yields:

\(-m_1C \Delta T_1 = m_2C\Delta T _2\)

We can solve for m₁:

\(\displaystyle \begin{aligned} m_1 &= -\frac{m_2 C\Delta T_2}{ C \Delta T_1} \\ \\ & = -\frac{m_2\Delta T_2}{\Delta T _1}\end{aligned}\)

The desired final temperature of water is 36.2 °C. Substitute and evaluate:
\(\displaystyle \begin{aligned} m_1 & = -\frac{(200\text{ mL})(36.2\text{ $^\circ$C}-29.5\text{ $^\circ$C})}{(36.2\text{ $^\circ$C}-84.5\text{ $^\circ$C})} \\ \\ & = -\frac{(200\text{ mL})(6.7\text{ $^\circ$C})}{-49.2\text{ $^\circ$C}}\\ \\ & =27\text{ mL}\end{aligned}\)

In conclusion, about 27 mL of water should be added.

Answer:

[See Below]

Explanation:

✦ A beaker of liquid would measure the volume of a liquid.

✦ A graduated cylinder is good for estimating the volume of a liquid.

✦ You'd most likely use a tape measure to measure the wall length and width.

~Hope this helps Mate. If you need anything feel free to message me.

The pH before any base is added is 5.07.


To find the pH before any base is added, we need to use the equation for the dissociation of hydrocyanic acid:

HCN + H₂O ⇌ H₃O+ + CN-

The Ka for this reaction is 4.9 x 10-10. We can set up an ICE table to find the concentration of H₃O+ at equilibrium:
HCN + H₂O ⇌ H₃O+ + CN-


I 0.150 M 0 0
C -x +x +x
E 0.150-x x x

The equilibrium expression for the dissociation of HCN is:

Ka = [H₃O+][CN-] / [HCN]

Substituting in the equilibrium concentrations from the ICE table, we get:

4.9 x 10-10 = (x)(x) / (0.150 - x)

Simplifying and solving for x, we get:

x = 2.21 x 10-6 M

This is the concentration of H3O+ at equilibrium, so we can use the pH equation to find the pH:

pH = -log[H₃O+]

pH = -log(2.21 x 10-6)

pH = 5.07

Therefore, the pH before any base is added is 5.07.

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Answer: \(2168 ^{\circ} \text{C}\)

Explanation:

For this question, we can use the formula \(Q=mc \triangle T\), where \(Q\) is the amount of heat absorbed, \(m\) is the mass of the sample, \(c\) is the specific heat constant, and \(\triangle T\) is the change in temperature (final temperature minus initial temperature as stated in the question).

From the question, we know that \(m=175, Q=1.57 \times 10^{6}\). Furthermore, we know that \(c=4.18\) (this is just a fact).

So, we get that \(1.57 \times 10^{6}=175(4.18)(\triangle T)\), meaning \(\triangle T=2146\).

Thus, \(t_{f}-22.0=2146 \longrightarrow t_{f}=\boxed{2168 ^{\circ} \text{C}}\)