What element is the most abundant in stars including the sun?

The percent purity of strontium hydroxide in the mass of the given sample is 74.7%.

The percent purity of a substance is the ratio of the actual amount of a substance present in a sample and the ratio of the whole amount of the sample.

Equation of reaction: Sr(OH)₂ + 2 HCl ---> SrCl₂ + 2 H₂O

The mass of the pure strontium hydroxide is calculated as follows:

moles of initial HCl sample = 0.1010 * 120 mL * 1 L / 1000 mL

moles of initial HCl sample = 0.01212 moles

Moles of HCl that reacted with NaOH = 0.1020 * 36.6 * 1 L / 1000 mL

Moles of HCl that reacted with NaOH = 0.00373 moles

moles of HCl that reacted with strontium hydroxide = 0.01212 - 0.00373

moles of HCl that reacted with strontium hydroxide  = 0.00839 moles

Moles of strontium hydroxide that reacted with HCl = 0.00839/2 moles

Mass of strontium hydroxide that reacted with HCl = 0.00839/2 moles * 121.63 g/mol

Mass of strontium hydroxide that reacted with HCl = 0.510 g

Percent purity = 0.510/0.683 * 100 %

Percent purity = 74.7%

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I₂ is the halogens which is darkest in colour than other.

Halogens are the elements which belongs to group 17. Group 17 elements are known as halogens. They are highly electronegative in nature.

The last electronic configuration is ns2 np5. Since, one electron is less to get stable electronic configuration. Therefore, they accept one electron and get stable electronic configuration.

As we move down the group, the darkness of colour increases. This is due to ionization energy which decreases as we move down the group. This is due to increase in the atomic size and decrease in nuclear form which further make high energy level to absorb lesser light and reflects deepen colour on moving down the group. Due to which they appears dark. Therefore, option A is the correct option.

Thus, we can concluded that I₂ is the halogens which is darkest in colour than other.

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Answer: 40 g/mol

Explanation:

Since each element has a distinct range of energy levels, the lines in an emission spectrum will be bright while those in an absorption spectrum would be dark. This makes spectra useful for identifying the various elements in a sample.

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The kinetic energy of the oxygen gas under the same condition is the same as that of helium.

We know that the kinetic energy of a gas depends on the temperature of the molecules of the gas. Temperature is the measure of the average kinetic energy of the molecules of the gas.

When we know that we have two gases, what would determine the average kinetic energy of the molecules of the gas would only be the temperature of the gas. Thus irrespective of the molar masses of the gases, they would have the same kinetic energy at the same temperature.

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According to the concept of solubility, isopropanol is miscible with water and hence there is one layer that is formed when water and isopropanol are  mixed.

Solubility is defined as the ability of a substance which is basically solute to form a solution with another substance. There is an extent to which a substance is soluble in a particular solvent. This is generally measured as the concentration of a solute present in a saturated solution.

The solubility mainly depends on the composition of solute and solvent ,its pH and presence of other dissolved substance. It is also dependent on temperature and pressure which is maintained.Concept of solubility is not valid for chemical reactions which are irreversible. The dependency of solubility on various factors is due to interactions between the particles, molecule or ions.

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It is not necessary to test the reactivity of the elemental metals with solutions of the same metal ion because it won't react with itself.

This is referred to as the relative capacity or how readily a substance undergoes a chemical reaction.

Reactivity of elements are dependent on various types of parameters such as the number of valence electrons, shells etc and can be tested with other substances. However, it can't be tested with the solutions of the same metal ion because no reaction will occur thereby making it the most correct reason in this scenario.

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Equivalent of sulfate ions = 4.00 EqSO4^2−

1) equivalent weight of sulphate = 96.0636/2

= 48.0328 g/equivalent

2) 2 mol will have a weight of = 2*96.0636 = 192.1272 g

3) so the equivalent of sulphate = 192.1272/48.0328

= 3.999, round it up to 4.00

Sulfur and oxygen atoms make up the majority of the sulphate ion's mass. Four oxygen atoms that are placed at equal intervals around the centre sulphur atom in this structure. In terms of bonding, two oxygen atoms make S=O bonds, while the other two form S-O bonds.

Two double bonds and two single bonds with O make up the more stable structure of SO42-, however the single bonds have a formal charge of -1.

An insoluble precipitate of BaSO4 forms when aqueous barium chloride is introduced to an acidified solution containing sulphate ions. This precipitate, which is white in colour, proves that sulphate is present.

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The balanced equation among the following is H2SO4 + 8HI -----> H2S +4I2 + 4H2O.

What is balanced equation?

A balanced equation is the equation in which both the reactants and products side will have equal number of atoms or ions. It helps us to count the number of moles of reactants and products involved in the reactions. The charges on both the sides need to be equal as well.

In the first option, 1 mole of sulfuric acid is reacting with 8 moles of hydrogen iodide to give 1 mole of hydrogen sulfide, 4 moles of iodine and 4 moles of water making it balanced equation on both reactant and product side.  

Therefore, the first option is balanced equation on both the sides that is reactants and products as H2SO4 + 8HI -----> H2S +4I2 + 4H2O.

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Answer: H2SO4 + 8HI -----> H2S +4I2 + 4H2O.

Explanation:

i just took it

Answer: 2.06%

Explanation:

The chemical formula for sulfuric acid is H₂SO₄.

Find the molar mass of the whole compound:

2(1.01) + 32.07 + 4(16) = 98.02 g/mol

The percent composition by mass of hydrogen can be calculated as:

[tex]\frac{2.02}{98.02}*100=0.0206*100=2.06[/tex]

Taking into account the definition of pH and pOH, for 8.68×10⁻³ M LiOH, the [OH⁻] is 8.68×10⁻³ M and the [H₃O⁺] is 1.148×10⁻¹² M.

pH is a measure of acidity or alkalinity that indicates the amount of hydrogen ions present in a solution or substance.

The pH is defined as the negative base 10 logarithm of the activity of hydrogen ions, that is, the concentration of hydrogen ions or H₃O⁺:

pH= - log [H⁺]= - log [H₃O⁺]

Similarly, pOH is a measure of hydroxyl ions in a solution and is expressed as the logarithm of the concentration of OH⁻ ions, with the sign changed:

pOH= - log [OH⁻]

The following relationship can be established between pH and pOH:

pOH + pH= 14

A strong base is a base that completely dissociates in aqueous solution. That is, in the ionization process they are completely transformed into cations or positive ions and into anions or negative ions, all concentrations being equal.

LiOH is a strong base, so [LiOH]=[OH⁻]= 8.68×10⁻³ M

Replacing in the definition of pOH:

pOH= - log 8.68×10⁻³ M

Solving

pOH= 2.06

So, pH is calculated as:

pH + 2.06= 14

pH= 14 - 2.06

pH= 11.94

Replacing this value in the definition of the pH:

- log [H₃O⁺]= 11.94

Solving:

[H₃O⁺]= [tex]10^{-11.94}[/tex]

[H₃O⁺]= 1.148×10⁻¹² M

In summary, the [OH⁻] is 8.68×10⁻³ M and the [H₃O⁺] is 1.148×10⁻¹² M.

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The net ionic equation is;

[tex]2PO_{4} ^{3-} (aq) + 3Sr^{2+} (aq) ----- > Sr_{3} (PO_{4})_{2} (s)[/tex]

The net ionic equation  has to do with the equation that  shows the ions that have undergone changes in the system. We know that the first step as we are tying to obtain the net ionic equation must be to write down the molecular equation of the reaction which we have have done here as

;[tex]2Na_{3} PO_{4} (aq) + 3SrCl_{2} (aq) ----- > Sr_{3} (PO_{4})_{2} (s) + 6NaCl(aq)[/tex]

We can see that the ions that had to be changed in the process are the phosphate ion and the phosphate ion. It was the both ions that were combined to obtain the precipitate thus they are more in the solution and they have to appear in our net ionic equation for this reaction.

Thus, in a nut shell, the ions that are going to occur in the net ionic equation are the ions that were combined as we can see to give the precipitate here.

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Answer:

Science. Chemistry. Chemistry questions and answers. How many equivalents of Mg2+ are present in a solution that contains 2.65 moles of Mg2+ ? Express your answer using three …

Expert Answer. 100% (5 ratings) Number of equivalents of an ion …. View the full answer. Transcribed image text: Question 4 (0.5 points) How many equivalents of Mg2+ are present in …

how many equivalents of Mg2+ are present in a solution that contains 2.75 mol of Mg2+?

A:

5.50 eq

Explanation:

The pressure of hydrogen gas exert before its volume was decreased is equal to 3.68 atm.

Boyle’s law states that the pressure exerted by a given mass of gas is inversely proportional to the volume occupied by it when the temperature of the gas remains constant.

The pressure (P) and volume (V) have an inverse relationship to each other as long as the temperature is kept constant.

P ∝ 1/V

or

P₁V₁ = P₂V₂                                        ................(1)

Given, the final pressure of the hydrogen gas,  P₂ = 9.67 atm

The initial volume of the hydrogen gas, V₁ = 10.84 L

The final volume of the hydrogen gas, V₂ = 4.13 L

Substitute volume and pressure in equation (1) to get the initial pressure:

P₁ × (10.84 L) = (9.67 atm) × 4.13

P₁ = 3.68 atm

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Answer:

When the electrons move from the cathode to the anode, they increase the chemical potential energy, charging the battery when they move the other direction, they convert this chemical potential energy to electricity in the circuit and discharge the battery.

Explanation:

The volume of the KOH required to neutralize 40.0 mL of a 0.035 M H2sO4 solution is 0.0215 L.

Concentration is the abundance of a constituent divided by way of the overall volume of an aggregate. several sorts of mathematical descriptions may be outstanding: mass concentration, molar concentration, variety concentration, and extent awareness.

Given

V1 =?

C₁ = 0.65 M

C₂ = 0.035 M

n -2

V2 = 40 ml  = 0.04 L

C₁V₁ = C₂V₂

V₁ = C₂V₂/ C₁

    =   0.035 * 0.04 / 0.065

    =  0.0215 L

The concentration of a substance is the quantity of solute found in a given amount of solution. Concentrations are normally expressed in terms of molarity, defined because of the variety of moles of solute in 1 L of answer.

The Concentration of an answer is a measure of the quantity of solute that has been dissolved in a given amount of solvent or answer. A concentrated answer is one that has a rather huge quantity of dissolved solute.

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Answer:

The relative atomic mass of element Z in this sample is 70.

Explanation:

The relative atomic mass of element Z in this sample is 69.6.

Answer:

............

.............................

The appropriate values for A and Z and the chemical symbol for X in the alpha decay of protactinium-231 is

Alpha decay is a radioactive decay by emitting an alpha particle, which is a positively charged nucleus of a helium-4 atom (consisting of two protons and two neutrons), emitted as a consequence of radioactivity.

Alpha has a symbol of α-particle. According to this question, protactinium-231 undergoes alpha decay, which means that it will lose 4 in its mass number and 2 in its atomic number.

231 - 4 = 227

91 - 2 = 89

The element that will be formed from the alpha decay will have a mass number of 227 and an atomic number of 89.

The element with an atomic number of 89 is actinium with chemical symbol Ac.

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At STP, 4.00 L of a pure gaseous substance has a mass of 10.0 grams. The molecular weight of this substance is is 56 g/mol.

The ideal gas equation is here:

P V = n RT

where,

P = pressure = 1 atm

V = volume = 4 L

R = 0.082 L atm  /K mol

T = temperature = 273 K

n = (1 × 4 ) / (0.082 × 273)

n = 0.178 mol

mass = 10 g

molecular weight  = moles / mass

                                = 10 / 0.178

                                = 56 g/mol

Thus, At STP, 4.00 L of a pure gaseous substance has a mass of 10.0 grams. The molecular weight of this substance is is 56 g/mol.

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Answer: Decomposition reaction

Explanation:

      This reaction type is a decomposition reaction. The single compound reactant is "breaking up" into two or more products.

Catalase best describes an enzyme that catalyzes a reaction involving the reduction of hydrogen peroxide with the oxidation of the second molecule of hydrogen peroxide.

Catalase is a common enzyme determined in almost all dwelling organisms exposed to oxygen (consisting of microorganisms, vegetation, and animals) which catalyzes the decomposition of hydrogen peroxide to water and oxygen. it's by far a totally crucial enzyme in defending the cell from oxidative damage by reactive oxygen species (ROS).

An enzyme is an organic catalyst and is sort of usually a protein. It quickens the fee of a selected chemical reaction within the cellular. The enzyme isn't destroyed at some stage in the reaction and is used again and again. Enzymes are categorized into six classes consistent with the form of reaction catalyzed: Oxidoreductases, transferases, hydrolases, lyases, ligases, and isomerases.

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70 mL of hot water are required. Increase in the temperature of the cold water, where water's specific heat capacity is 4.184 J/g and its density is 1.00 g/mL. Here, the mass of the cold water is equal to 30 mL times the density of one gram per milliliter, or 30g.

A instrument is a machine that calculates how much heat is generated during a physical or chemical process. For instance, when an exergonic reaction takes place in solutions in a measuring device, the solution absorbs the heat created by the process, raising its temperature.

To gauge a body's temperature fluctuations, a calorimeter is utilized. Calculating enthalpy, stability, heat capacity, and other thermochemical quantities often involves the use of calorimetry.

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Ions can be made by single element or covalently bonded group of elements. The covalently bonded group of elements is called polyatomic ions or polyatomic atoms. Therefore, to become P³⁻,  phosphorous has to gain 3 electrons in its p orbital.

Any species that contain charge whether it is positive charge or negative charge is called ions. The example of polyatomic ions are sulfate, phosphate, nitrate etc.

Cation is the species that loose electron and attain positive charge while anion is a species which gain electron and attains negative charge so when anion and cation combine in fixed ration the the overall charge of the molecule is zero that is molecule is neutral, the charge over cation and anion is also called oxidation state.

The electronic configuration of phosphorous is Ne 3s² 3p³. To become P³⁻. Phosphorous has to gain 3 electrons in its p orbital.

Therefore, to become P³⁻,  phosphorous has to gain 3 electrons in its p orbital.

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Answer:

Forensic anthropology is the study of human remains in order to solve crimes or to determine the identity of a deceased individual.

Explanation:

Answer:

c 8id

Explanation:

Manganese, Mn, forms two ions, one with a 2+ charge and one with a 3+ charge.  the formula for manganese (II) sulfide is MnS.

The manganese atomic number is 25. the manganese is the metal . metal have tendency to donate valence electron. manganese donate 2 electrons and form Mn⁺². The sulfur atomic number is 16. sulfur is nonmetal and tendency to accept electrons. sulfur accepts electrons and form S²⁻. The manganese and sulfur thus combines and form ionic compound. the formula for ionic compound manganese(II)sulfide is  MnS

Thus, Manganese, Mn, forms two ions, one with a 2+ charge and one with a 3+ charge.  the formula for manganese (II) sulfide is MnS.

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The reagents in a test tube should never be shaken by keeping a finger on its mouth because, you would contaminate the other reagents when same finger is used for other test tubes. Instead you can use a shaker in the laboratory.

What is a shaker in laboratory?

Shaker is a laboratory equipment which can be used to blend, mix or agitate samples in the tube. There are different types like vortex shaker, orbital shaker, platform shaker and incubator shaker.

The samples in the test tubes can easily get contaminated when it is shaken with a finger. Also, if you are sensitive to some chemicals your hands can burn or may cause irritation if shaker is not being used in shaking.

Therefore, shaker is a better option to mix the reagents in a test tube than shaking the test tube by closing its mouth with a finger.

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Fe(OH)2 doesn't react with water. Fe(OH)2 is said to have a solubility constant that ranges from 8x10-16 to 2x10-15.

Fe(OH)2 is significantly more soluble than Fe(OH)3, which has a solubility constant in the range of 10-38.

Fe(OH)2 is incredibly insoluble when compared to NaCl (Ksp of roughly 4x101!!! ).

Consequently, perspective is key.

The aqueous solution numbers are in the morning. In the early history of the earth (the "oxygen catastrophe"), the numbers for Fe(II) and Fe(III) were extremely important.

They shouldn't be directly compared because the three solubility products have different dimensions (officially, Fe(OH)3 splits into four ions, Fe(OH)2 splits into three, and NaCl splits into two). However, because of how far apart they are, the morning conclusions remain valid.

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