In the titration of 25.0 mL of 0.1 M HCl with 0.1 M NaOH, how is the pH calculated before the titrant is added

Answer:

A. True

B. False

Explanation:

Reaction between hypochlorous acid and ammonia does not yields a Ph value of 7.00 , this value is defined to water and no other reaction can yield exactly this Ph value. The acid reaction will give a Ph value below 7 while a base reaction will give Ph value of above 7.

diseases caused by viruses: smallpox

                                               measles, mumps, rubella

                                               hepatitis

                                               herpes

Answer:

Ebola , chicken pox , Gastroenteritis, Dengue, Yellow Fever .

Explanation:

Virus is something that every one can get it and also they can catch it easily.

The thermodynamic quantity that expresses the extent of randomness in a system is entropy.

A state of disorder, unpredictability, or uncertainty are frequently related with the scientific concept of entropy, which is also a quantifiable physical characteristic. The notion and the phrase are employed in a variety of disciplines, including classical thermodynamics, where they were initially identified, statistical physics, which describes nature at the molecular level, and information theory and entropy. It has wide-ranging uses in physics and chemistry, biological systems and how they relate to life, cosmology, economics, sociology, weather science, and information systems, particularly the transfer of information through telecommunication.

In 1850, the Scottish engineer and physicist Macquorn Rankine used the terms thermodynamic function and heat potential to describe the thermodynamic notion and entropy.

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A solution of phosphoric acid (H3PO4) has a pH of about 1.0 at a concentration of 0.20 M.

Phosphoric acid (H3PO4) is a triprotic acid, meaning it has three dissociable hydrogen ions. As a result, its pH is determined by the concentration of each ion. For a 0.20 M solution of H3PO4, the pH can be calculated as follows:

Step 1: The first dissociation reaction of H3PO4 is \(H3PO4 + H2O → H2PO4- + H3O+\). The equilibrium constant for this reaction (Ka1) is \(7.5 × 10-3\). This means that only a small amount of H3PO4 will dissociate into H2PO4- and H3O+.

Step 2: The second dissociation reaction of \(H2PO4- is H2PO4- + H2O → HPO42- + H3O+\). The equilibrium constant for this reaction (Ka2) is \(6.2× 10-8\\\). This means that even less H2PO4- will dissociate into HPO42- and H3O+.

Step 3: The third dissociation reaction of \(HPO42- is HPO42- + H2O → PO43- + H3O+\). The equilibrium constant for this reaction (Ka3) is \(4.2 × 10-13\). This means that almost no \(HPO42-\)will dissociate into PO43- and H3O+.

Since the first dissociation is the most significant for a 0.20 M solution of H3PO4, we can calculate the pH as follows:\(Ka1 = [H2PO4-][H3O+] / [H3PO4]7.5 × 10-3 = [H2PO4-][H3O+] / 0.20[H3PO4]H3O+ = √(0.20 × 7.5 × 10-3)H3O+ = 0.048 M-pH = -log[H3O+]pH = -log(0.048)pH = 1.3\)

Therefore, a solution of phosphoric acid (H3PO4) has a pH of about 1.0 at a concentration of 0.20 M.

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Answer: because acid and water react in a vigorous exothermic reaction, releasing heat, sometimes boiling the liquid.

Answer:

No

Explanation:

In the hot pack, as the water reacts with the magnesium sulfate, the pack becomes bigger is not an indication that new atoms have been created or produced.

As with all chemical reactions, they all obey the law of conservation of matter which states that "in chemical reactions, matter is neither created nor destroyed but atoms simply recombine".

The reason why the hotpack becomes bigger is because the atoms gain more volume.

Answer:

A calorie is the amount of energy needed to raise the temperature of 1 gram of water 1 degree Celsius. The complete combustion of a large kitchen match, for example, gives you about one kilocalorie of heat

The name of the compound with the chemical formula Br2F8 is dibromo octafluorine.

The chemical formula of a compound shows the type and proportion of each element that makes up the chemical compound.

According to this question, a compound with chemical formula Br2F8 is given. The compound consists of the following:

Therefore, the name of the compound with the chemical formula Br2F8 is dibromo octafluorine.

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Answer:

A, C, E

Explanation:

hope this helps

The true statements are - Cells come in different sizes and shapes, some organisms are made of just one cell and most cells are too small to see with the eye. Thus, the correct options are options A, C and E.

Cells are the basic structural and functional units of life. They are the smallest entities that can carry out the fundamental processes necessary for an organism's survival.

Cells are enclosed by a cell membrane, which separates the internal components from the external environment. Inside the cell, various parts perform specific functions, such as energy production, protein synthesis, and storage of genetic material.

Cells can be categorized into two broad types: prokaryotic cells, which lack a nucleus and eukaryotic cells, which have a nucleus.

Thus, the ideal selection is option A, C and E.

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Answer:

magnesium and oxygen

Explanation:

Answer:

mass(m)=26.4g

volume (v)=3.0cm²

we have

density =m/v=26.4/3=8.8g/cm³

since it is equal to density of nickel.

Option C nickel is a required answer.

Answer:

\(\huge\boxed{\fcolorbox{green}{yellow}{option \: \: c}}\)

Answer:

Mass of CO2 WILL BE ~ 9.33 g

Explanation:

Moles of O2 = 14/18

Let the mass of CO2 be x

Then moles of CO2 will be = x/12

moles of CO2 = moles of O2

x/12 = 14/16

x = 9.33 grams

Answer:

0.200 M

Explanation:

Step 1: Given data

Step 2: Calculate the moles (n) of CoCl₂ (solute)

We will use the following expression.

n = m / M

n = 2.60 g / (130. g/mol) = 0.0200 mol

Step 3: Calculate the molar concentration of the solution

Molarity is equal to the moles of solute divided by the liters of solution.

M = n/V

M = 0.0200 mol/0.100 L = 0.200 M

The addition of 1.25 g of sodium formate increases the pH of the solution by 2.12 units.

To calculate the change in pH, we need to determine the new concentrations of the formic acid and its conjugate base after the addition of the sodium formate. We can then use the Henderson-Hasselbalch equation to calculate the new pH.

First, let's calculate the initial concentration of formic acid:

0.50 M = moles of formic acid / 0.027 L

moles of formic acid = 0.50 x 0.027 = 0.0135 mol

Now, we need to calculate the concentration of formate ion (HCOO-) after adding 1.25 g of sodium formate (HCOONa) to the solution. Since sodium formate dissociates completely in water, the number of moles of formate ion added will be the same as the number of moles of sodium formate:

moles of HCOO- = moles of NaHCOO = 1.25 g / (68.01 g/mol) = 0.0184 mol

Next, we can calculate the new concentrations of formic acid and formate ion:

[ HCOOH ] = (0.0135 mol) / (0.027 L) = 0.5 M

[ HCOO- ] = (0.0135 mol + 0.0184 mol) / (0.027 L) = 1.15 M

Now, we can use the Henderson-Hasselbalch equation to calculate the new pH:

pH = pKa + log([ HCOO- ] / [ HCOOH ])

pKa = -log(Ka) = -log(1.8 x 10^-4) = 3.74

pH = 3.74 + log(1.15 / 0.5) = 3.74 + 0.40 = 4.14

Therefore, the change in pH is:

ΔpH = 4.14 - 2.02 = 2.12

So, the addition of 1.25 g of sodium formate increases the pH of the solution by 2.12 units.

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The amount of zinc metal in grams consumed in the given reaction is 20.27g.

The mass of a substance in a stoichiometric calculation can be proceeded as follows;

According to this question, a sample of zinc metal reacts completely with an excess of hydrochloric acid. The number of moles of the hydrogen gas produced can be calculated thus;

PV = nRT

0.980 × 7.8 = n × 0.0821 × 298

7.644 = 24.47n

n = 0.31 moles.

In the reaction, 1 mole of zinc metal produces 1 mole of hydrogen gas. Hence, 0.31 moles of zinc metal will be required to produce 0.31 moles of hydrogen gas.

mass of Zn = 0.31 mol × 65.38g/mol = 20.27g

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Answer:

a

Explanation:

40 Ne has 10 electrons which consist of 10 protons and 10 neutrons

Neon is a chemical element which is rare gas or noble gas as it has a stable octet electronic configuration, meaning it has 8 valence electrons in its outermost shell.

Neon belongs to group 0/VIII and period 1 of the periodic table.

An element is a substance which takes part in a chemical reaction. There are different classes of elements which includes the metals, nonmetals and the metalloids.

So therefore, 40 Ne has 10 electrons which consist of 10 protons and 10 neutrons.

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180°: Linear, VSEPR number 2

107°: Trigonal bipyramidal, VSEPR number 5

120°: Trigonal planar, VSEPR number 3

Molecular geometry refers to the three-dimensional arrangement of atoms in a molecule. It determines the shape of the molecule and the relative positions of its atoms in space. The molecular geometry is determined by the number of atoms and the types of bonds between them.

The concept of molecular geometry is important in chemistry because it determines the physical and chemical properties of the molecule, such as its reactivity, polarity, and biological activity.

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Answer:

All of the above

Explanation:

I chose Option C because a living organism contains DNA and it can reproduce made of cells with membrane bound nucleus.

The compound in which nitrogen has an oxidation number of -3 is  \(NH_3\) (ammonia).

In \(NH_3\) , the nitrogen atom has an oxidation number of -3. This is because each hydrogen atom in \(NH_3\) has an oxidation number of +1, and the sum of the oxidation numbers in a neutral molecule is zero.

Since ammonia is neutral, the total of the hydrogen atoms' oxidation numbers must balance out the overall charge, resulting in nitrogen having an oxidation number of -3.

Let's look at the other compounds listed:

        nitrogen.

        Oxygen typically has an oxidation number of -2 in compounds, so if    

        we assume the oxidation number of oxygen as -2, the sum of the  

        oxidation numbers for nitrogen in \(N_2O_5\) would be +10 (since there

         are five oxygen atoms).

        The, nitrogen in \(N_2O_5\) does not have an oxidation number of -3.

       Since the molecule is neutral, the nitrogen atom must have an

         oxidation number of +2 to balance out the overall charge.

         The, nitrogen in NO does not have an oxidation number of -3.

        oxidation number of -2, following their usual oxidation state.

        To balance out the overall charge of the molecule, the nitrogen    

         atom in\(NO_2\) has an oxidation number of +4.

        The nitrogen in \(NO_2\) does not have an oxidation number of -3.

In summary, among the compounds listed, \(NH_3\) (ammonia) is the only one where nitrogen has an oxidation number of -3.

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The density of the metal is 1.23 g/mL.

The density of the metal in g/mL can be calculated by using the formula:

density = mass/volume.

Given that the mass of the metal is 49 g and the volume of water displaced is (72.22 mL - 32.55 mL = 39.67 mL), we can substitute these values into the formula to find the density.

Density = 49 g / 39.67 mL

To express the answer to the correct number of significant figures, we need to determine the least number of significant figures in the given values. The volume measurement has the least number of significant figures (4), so the density should also be expressed to 4 significant figures.

Therefore, the density of the metal is 1.23 g/mL.

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Answer:

Decreases

Explanation:

The temperature decreases when latitude increases.

In a one-dimensional infinite potential well, the allowed energy levels are given by the equation:

E_n = (n^2 * h^2)/(8mL^2)

where n is the quantum number, h is Planck's constant, m is the mass of the electron, and L is the length of the well. Since we have five electrons, according to the Pauli exclusion principle, each energy level can accommodate a maximum of two electrons with opposite spin.

The ground state of the system is when all the electrons occupy the lowest energy level, which corresponds to n = 1. Therefore, the energy of the ground state is:

E_1 = (1^2 * h^2)/(8mL^2)

The value of (S_z), which represents the z-component of the total spin angular momentum, can be determined by considering the spin of the individual electrons. Since we have five electrons, each with a spin of 1/2, the total spin can range from -5/2 to 5/2 in steps of 1.

In the ground state, the total spin (S) will be the sum of the individual spins of the electrons. Since the exclusion principle is in effect, the ground state will have the maximum total spin, which is (5/2). Therefore, the energy of the ground state of the system is given by E_1, and the (S_z) of the ground state is 5/2.

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Answer:

planets,meteoroids and asteroids  

Explanation:

At equilibrium, the concentrations of A, B, and C are 0.112 M, 0.212 M, and 0.188 M, respectively.

The standard free-energy change (ΔG°) of reaction is -3.06 kJ/mol, which can be related to equilibrium constant (K) using following equation:

ΔG° = -RTlnK

where R is gas constant (8.314 J/mol·K),

T is temperature in Kelvin (25°C = 298 K), and

ln is natural logarithm.

-3.06 kJ/mol = -8.314 J/mol·K x 298 K x lnK

Solving for lnK:

lnK = -3.06 kJ/mol / (-8.314 J/mol·K x 298 K) = 0.447

Taking, antilogarithm of both sides to solve for K:

K = e^0.447 = 1.563

At equilibrium, concentrations of A, B, and C can be calculated using stoichiometry of the reaction and equilibrium constant expression:

K = [C] / ([A] x [B])

1.563 = [C] / (0.30 M x 0.40 M)

[C] = 0.188 M

Since, stoichiometry of reaction is 1:1:1, [A] and [B] at equilibrium will be:

[A] = [A]0 - [C] = 0.30 M - 0.188 M = 0.112 M

[B] = [B]0 - [C] = 0.40 M - 0.188 M = 0.212 M

Therefore, at equilibrium, the concentrations of A, B, and C are 0.112 M, 0.212 M, and 0.188 M, respectively.

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Answer:

Derrik left an ice cube in a cup. After an hour, the ice had changed into liquid water. The liquid water has the same _______ as the solid ice cube.

Explanation:

The scatter plot is a graph that shows the relationship between two variables. In this case, the x-axis represents the date, and the y-axis represents the number of customers without power.

The scale on the x-axis could be labeled with the dates from Sept. 6 to Sept. 13, and the scale on the y-axis could be labeled with increments of 200,000 or 250,000 to accommodate the data range. The title for the x-axis could be "Date" and for the y-axis could be "Number of Customers Without Power." To find the linear regression model that fits the data, we can use the method of least squares. The equation for the line of best fit would be: y = mx + b, where y represents the number of customers without power and x represents the date. By analyzing the data, we can find the slope (m) and the y-intercept (b) values. To sketch the scatter plot with the line superimposed over the data, we would plot each data point as a dot on the graph. Then, we would draw the line of best fit using the linear regression equation we found in step 2. The scale on the x-axis and y-axis would remain the same as mentioned in step 1.

The slope of the line represents the rate of change in the number of customers without power per day. In this case, it indicates how many customers were getting their power restored each day on average. The y-intercept represents the initial number of customers without power on the first day of the data set. To forecast the number of customers without power on September 16, we would use the linear regression equation from step 2 and substitute the date (x) as September 16. This would give us the predicted value for that date. The goodness of fit of the line can be evaluated by calculating the coefficient of determination (R-squared value). This value ranges from 0 to 1 and represents the proportion of the variation in the dependent variable (number of customers without power) that can be explained by the independent variable (date). A higher R-squared value indicates a better fit of the line to the data.

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Answer:

a bus moves on a straight road then makes a right turn

Explanation:

yes