Metals present in municipal wastewater may still be present in treated sewage sludge; ______

Answer:The specific heat of the unknown substance is 1.22 J/ °Cg.

Explanation:

Heat absorbed by the water .

Mass of the water = 110.0 g

Change in temperature of water = [tex]\Delta T=32.4^oC-24.2^oC=8.2^oC[/tex]

[tex]Q=mc\Delta T=110.0g\times 4.18 J/^oCg\times 8.2^oC=3,770.36 J[/tex]

Heat lost by substance(Q') = Heat gained by the water(Q)

-Q' = Q

Change in temperature of the substance =

[tex]\Delta T'=(32.4^oC)-105.0^oC=-72.6 ^oC[/tex]

Mass of the substance = m'=42.5 g

Specific heat of substance = c'

[tex]-(m'\times c'\times \Delta T')=3,770.36 J[/tex]

[tex]c'=\frac{3,770.36 J}{42.5 g\times 72.6^oC}=1.22 J/^oCg[/tex]

The specific heat of the unknown substance is 1.22 J/ °Cg.

Scientific theories become stronger over time primarily because scientists continuous attempt to challenge and refine them, which leads to improvements and adjustments that further solidify the theory.

The best explanation for why scientific theories grow stronger over time is option A: 'As more scientist attempt to find holes in the current theory adjustments are made which make the theory stronger.' Scientific theories are rigorously tested and often challenged by researchers who seek to uncover any weaknesses or inconsistencies. When such efforts are made, they can lead to refinements and adjustments that subsequently strengthen the theory. This process may involve incorporating new evidence, reinterpreting existing data, or modifying theoretical frameworks to better explain the phenomenon in question.

Scientific theory is not just an educated guess; it is a comprehensive explanation supported by many research studies that collectively provide falsifiable evidence. Throughout history, theories such as the heliocentric model have been revised and strengthened through this process. It is by this meticulous scrutiny, including the elimination of competing hypotheses and the aggregation of reliable evidence, that a scientific theory matures and gains acceptance.

The statement which best explains why scientific theories grow stronger over time is A.) As more scientists attempt to find holes in the current theory, adjustments are made which make the theory stronger.

Scientific theories are dynamic and grow stronger through a process of rigorous testing, criticism, and refinement. When scientists develop a theory, they propose explanations for phenomena observed in the natural world. These theories are not merely guesses; they are grounded in substantial evidence that has been gathered through experimentation and observation. The process of scientific investigation includes trying to refute or find the limitations of current theories. As researchers explore these theories in different contexts and conditions, they either gather more evidence that supports the theory or uncover discrepancies that prompt modifications. This critical assessment and ongoing peer review contribute to the strength and reliability of scientific theories over time. Each time a theory withstands scrutiny or is adjusted to incorporate new data, it becomes more robust and dependable. Scientific theories are considered strong because they have been tested and falsified repeatedly, not because they are simply old or widely taught. It is the accumulation of evidence and the continuous critical analysis by the scientific community that gradually builds the strength of a theory.

Answer:

Deep geological disposal method

Explanation:

A deep geological disposal method is the most efficient method in disposing of the waste materials produced from a nuclear plant. These materials are disposed at a depth of usually about 200 to 1000 m below the surface and also from 1500 m to 5500 m below the surface. And it has to be below the groundwater level so that it does not contaminate it. So necessary precautionary measures are needed to be taken.

This method is used for the disposal of high and intermediate levels of nuclear waste often represented by HLW and ILW respectively.

Answer: 55.35ml

Explanation:

[tex]Ca+2HF\rightarrow CaF_2+H_2[/tex]

To calculate the given moles, we use the formula:

[tex]Moles=\frac{\text{Given mass}}{\text{Molar mass}}[/tex]

[tex]Moles=\frac{85.8g}{78g/mol}=1.1moles[/tex]

By  stoichiometry of the reaction,

1 mole of [tex]CaF_2[/tex]  is produced by 1 mole of Ca

1.1 moles of [tex]CaF_2[/tex]  are produced by=[tex]\frac{1}{1}\times 1.1=1.1 moles[/tex] of Ca.

Mass of [tex]CaF_2=\text{no of moles}\times \text{Molar mass}[/tex]

Mass of [tex]CaF_2=1.1\times {78}=85.8g[/tex]

[tex]Volume=\frac{Mass}{Density}[/tex]

[tex]Volume=\frac{85.8g}{1.55g/ml}=55.35ml[/tex]

Answer: Option (a) is the correct answer.

Explanation:

Molarity is defined as the number of moles present in a liter of solution.

Mathematically,       Molarity = [tex]\frac{\text{no. of moles}}{volume}[/tex]

Since, it is given that molarity is 4.0 molar or 4.0 m/L and no. of moles is 12 moles.

Therefore, calculate volume as follows.

                      Molarity = [tex]\frac{\text{no. of moles}}{volume}[/tex]

                         4.0 m/L = [tex]\frac{12 moles}{volume}[/tex]

                      volume = 3 L

Hence, we can conclude that volume of the given solution is 3 liters.

Final answer:

Baking soda, or sodium bicarbonate, when dissolved in water, has a basic pH close to 9.0, classifying it as a weak base.

Explanation:

When sodium bicarbonate, commonly known as baking soda, is dissolved in water, it exhibits basic properties. The pH of a baking soda solution is closest to 9.0, which means it is a weak base. Water is neutral with a pH of 7.0, whereas a substance with a pH higher than 7.0 is considered alkaline or basic.

The pH scale ranges from 0 to 14, with 7 being neutral. Acids have a pH less than 7, and bases have a pH greater than 7. The pH of a substance is determined by its concentration of hydronium ions. Baking soda has a lower concentration of hydronium ions compared to pure water, thereby making it a base with a pH higher than 7.

In practical applications, baking soda is used to neutralize acids, such as in bee sting treatments or when mixed with acetic acid in vinegar during bread preparation.

Final answer:

To calculate the mass percentages of Cl and Br in a mixture of AgCl and AgBr with 60.94% Ag by mass, we need additional data to determine the individual masses of Cl and Br. Without it, we cannot provide precise percentages.

Explanation:

The question is about calculating the mass percents of chlorine (Cl) and bromine (Br) in a mixture of silver chloride (AgCl) and silver bromide (AgBr) that contains 60.94% silver (Ag) by mass. The molar mass of silver (Ag) is 107.87 g/mol, for AgCl it is 143.32 g/mol (107.87 g/mol + 35.45 g/mol for Cl), and for AgBr it is 187.77 g/mol (107.87 g/mol + 79.90 g/mol for Br).

To find the mass percentages of Cl and Br in the mixture, we will first assume we have 100 grams of the mixture. Given the percent of silver, we can calculate the mass of silver in the mixture, which should be 60.94 grams. The remaining mass will be the combined mass of Cl and Br. However, without additional information such as the mass or molar ratios of AgCl to AgBr, we cannot precisely divide the remaining mass between Cl and Br. If such data were available, the mass percentages of Cl and Br could be found by calculating their individual masses and dividing by the total mass of the mixture, then multiplying by 100.

  CS2(l)  +Cl2(g)→CCl4(l)   + S2Cl2 (l)

The next  logical  step  in balancing  the  equation above is  place  the  coefficient  3  in front  of the chlorine  molecule  ( answer B)

  Explanation

When   coefficient 3  in placed in front  of   chlorine  molecule  the balanced equation is as below

The compound CH3-CH2-SH belongs to the organic family known as Thiols. Thiols are structurally similar to alcohols but the oxygen atom in alcohols is replaced by sulfur in thiols. Both thiols and alcohols belong to a larger class called the Hydrocarbon Derivatives.

The compound you mentioned, CH3-CH2-SH, falls into the organic family categorized as 'Thiols'. Thiols are similar to alcohols in structure, but they have a sulfur atom rather than an oxygen atom. They are identified by the -SH or sulfhydryl functional group. Like the hydroxyl group in an alcohol, this sulfhydryl group gives a thiol its properties.

For example, the compound CH3-SH, also known as 'Methanethiol', is analogous to the alcohol methanol. Both thiols and alcohols are part of a larger class called the 'Hydrocarbon Derivatives'. As the name suggests, these are derived from hydrocarbons by replacing one or more hydrogen atoms with a functional group, which in this case is either a hydroxyl group (-OH) for alcohols or a sulfhydryl group (-SH) for thiols.

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Answer: The molar mass of solute is 156 g/mol

Explanation:

Elevation in boiling point is defined as the difference in the boiling point of solution and boiling point of pure solution.

The equation used to calculate elevation in boiling point follows:

[tex]\Delta T_b=\text{Boiling point of solution}-\text{Boiling point of pure solution}[/tex]

[tex]\Delta T_b[/tex] = ? °C

Boiling point of pure water = 100°C

Boiling point of solution = 101°C  

Putting values in above equation, we get:

[tex]\Delta T_b=(101-100)^oC=1^oC[/tex]

To calculate the elevation in boiling point, we use the equation:

[tex]\Delta T_b=iK_bm[/tex]

Or,

[tex]\Delta T_b=i\times K_b\times \frac{m_{solute}\times 1000}{M_{solute}\times W_{solvent}\text{ (in grams)}}[/tex]

where,

[tex]\Delta T_b[/tex] = 1°C

i = Vant hoff factor = 1 (For non-electrolytes)

[tex]K_b[/tex] = molal boiling point elevation constant = 0.52°C/m.g

[tex]m_{solute}[/tex] = Given mass of solute = 300 g

[tex]M_{solute}[/tex] = Molar mass of solute  = ?

[tex]W_{solvent}[/tex] = Mass of solvent (water) = 1000 g

Putting values in above equation, we get:

[tex]1^oC=1\times 0.52^oC/m\times \frac{300\times 1000}{M_{solute}\times 1000}\\\\M_{solute}=156g/mol[/tex]

Hence, the molar mass of solute is 156 g/mol

Answer:

11 neutrons

Explanation:

Mass no. = 20

atomic no. = 9

no. of neutrons = mass number - atomic number

                          =   20 - 9

                          =     11 neutrons

[tex]\boxed{1.1255 \times {{10}^{23}}{\text{ atoms}}}[/tex] of oxygen are present in 7.00 g of sodium dichromate.

Further Explanation:

Given information:

Mass of sodium dichromate: 7.00 g

To calculate:

Number of oxygen atoms in 7.00 g of sodium dichromate

Steps to proceed:

I. First of all, moles of sodium dichromate that are present in 7.00 g of sodium dichromate are to be calculated. This is done with the help of equation (1) as mentioned below.

The formula to calculate moles of sodium dichromate [tex]\left( {{\text{N}}{{\text{a}}_{\text{2}}}{\text{C}}{{\text{r}}_{\text{2}}}{{\text{O}}_{\text{7}}}} \right)[/tex] is as follows:

[tex]{\text{Moles of N}}{{\text{a}}_{\text{2}}}{\text{C}}{{\text{r}}_{\text{2}}}{{\text{O}}_{\text{7}}} = \dfrac{{{\text{Mass of N}}{{\text{a}}_{\text{2}}}{\text{C}}{{\text{r}}_{\text{2}}}{{\text{O}}_{\text{7}}}}}{{{\text{Molar mass of N}}{{\text{a}}_{\text{2}}}{\text{C}}{{\text{r}}_{\text{2}}}{{\text{O}}_{\text{7}}}}}[/tex]                                               …… (1)

The mass of [tex]{\text{N}}{{\text{a}}_{\text{2}}}{\text{C}}{{\text{r}}_{\text{2}}}{{\text{O}}_{\text{7}}}[/tex] is 7.00 g.

The molar mass of [tex]{\text{N}}{{\text{a}}_{\text{2}}}{\text{C}}{{\text{r}}_{\text{2}}}{{\text{O}}_{\text{7}}}[/tex] is 261.97 g/mol.

Substitute these values in equation (1).

[tex]\begin{aligned}{\text{Moles of N}}{{\text{a}}_{\text{2}}}{\text{C}}{{\text{r}}_{\text{2}}}{{\text{O}}_{\text{7}}} &= \frac{{{\text{7}}{\text{.00 g}}}}{{{\text{261}}{\text{.97 g/mol}}}} \\ &= 0.0267{\text{ mol}} \\ \end{aligned}[/tex]  

II.Moles of oxygen that are present in 0.267 moles of sodium dichromate are to be calculated.

According to the chemical formula of sodium dichromate, it is evident that one mole of sodium dichromate contains two moles of sodium, two moles of chromium and seven moles of oxygen in it. Since one mole of sodium dichromate consists of seven moles of oxygen, moles of oxygen present in 0.267 moles of sodium dichromate can be calculated as follows:

[tex]\begin{aligned}{\text{Moles of oxygen}} &= \left( {0.0267{\text{ mol N}}{{\text{a}}_2}{\text{C}}{{\text{r}}_4}{{\text{O}}_7}} \right)\left( {\frac{{7{\text{ mol O}}}}{{{\text{1 mol N}}{{\text{a}}_2}{\text{C}}{{\text{r}}_4}{{\text{O}}_7}}}} \right) \\&= 0.1869{\text{ mol O}} \\\end{aligned}[/tex]  

III. Number of oxygen atoms that are present in 0.1869 moles of oxygen is to be calculated. This is done with the help of Avogadro’s law which states that one mole of a substance contains [tex]6.022 \times {10^{23}}{\text{ particles}}[/tex] . Such particles can be atoms, molecules, or formula units.

Since one mole of oxygen contains [tex]6.022 \times {10^{23}}{\text{ atoms}}[/tex], atoms of oxygen present in 0.1869 moles of oxygen can be evaluated as follows:

[tex]\begin{aligned}{\text{Number of oxygen atoms}} &= \left( {0.1869{\text{ mol}}} \right)\left( {\frac{{6.022 \times {{10}^{23}}{\text{ atoms}}}}{{{\text{1 mol}}}}} \right) \\&= 1.1255 \times {10^{23}}{\text{ atoms}} \\\end{aligned}[/tex]  

Hence, [tex]1.1255 \times {10^{23}}{\text{ atoms}}[/tex] of oxygen are present in 7.00 g of sodium dichromate.

Learn more:

Answer details:

Grade: Senior School

Subject: Chemistry

Chapter: Mole concept

Keywords: sodium dichromate, oxygen, mass, molar mass, 7.00 g, 1.1255*10^23 atoms, Avogadro’s law, one mole, atoms, molecules, particles.

Answer:-

Ni + CuSO4 --> NiSO4 + Cu

Explanation:-

The symbol for Nickel is Ni.

The Symbol for copper is Cu.

Copper Sulphate has the formula CuSO4.

If Nickel replaces copper from copper sulphate then nickel sulphate is formed.

Nickel sulphate has the formula NiSO4.

So the equation becomes

Ni + CuSO4 --> NiSO4 + Cu

Answer:

Density of the substance = 8.9 g/cm³

Explanation:

The volume of the substance = 10 cm³  

Mass = 89 gm

Density = mass / volume = 89 gm / 10 cm³ = 8.9 g/cm³

When we breathe red blood cells bond to the oxygen but when we inhale carbon monoxide (CO), it sticks to red blood cells and block the oxygen and suffocation occurs. It is also known as “Silent Killer”.

Headaches, nausea and fatigue are some of early symptoms of carbon monoxide poisoning. It is sometimes mistakenly identified as “Flu”. Because this gas cannot be detected at home. It is produced by common household appliances, if not proper ventilated, such as water heaters, generators, cars etc.

Carbon monoxide poisoning and acute toxicity are related and often confused due to similar symptoms such as headache, weakness, and even death.

Carbon monoxide poisoning occurs due to inhaling excessive levels of carbon monoxide (CO), which can lead to symptoms like headache, dizziness, weakness, and even death. This poisoning is sometimes mistakenly identified as acute toxicity due to exposure to carbon monoxide.

Answer:

Fusion.

Explanation:

The core squeezes together so tightly that four hydrogen nuclei combine to form one helium atom. This is the textbook definition of nuclear fusion.

Mole is equal to the Avogadro's constant. The 3.675 moles of NO is required to completely react with 2.45 mole of Ammonia.    

Mole:

One mole is the unit of measurement of small particles like ions, atoms , and molecules. It is equal to the Avogadro's constant.

Given reaction,

[tex]\bold{4 NH_3 + 6 NO \rightarrow5 N_2 + 6 H_2O}[/tex]

Means 4 moles of Ammonia react with 6 moles of NO in reaction. the molar ratio of ammonia and NO is 4:6.

Hence,

Moles of NO required

[tex]\Rightarrow\bold{\frac{6}{4} \times 2.45 = 3.675 mole}[/tex]          

Hence, we can conclude that the 3.675 moles of NO is required to completely react with 2.45 mole of Ammonia.    

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