Answer:
76
Explanation:
Alpha decay is one of the most basic forms of radioactive decay. It has an atomic mass of 4 and a proton number of two.
Undergoing an alpha decay will decrease the atomic mass by four and the atomic number by two.
In this particular question, we are particular about the atomic number. The atom has an atomic number of 78. So taking 2 off this gives 76
The atomic number of pt-175 after it undergoes alpha decay is 76
Radioactive decay is defined as the splitting of heavy unstable isotopes to two or more stable particles. The three main types of radioactive decay are
alpha decay (α-decay).beta decay (β-decay)gamma decay(γ-decay)An Alpha decay occurs when the radioactive nucleus releases a helium ion (alpha particle) leaving the daughter nucleus with a reduced atomic number by 2 and reduced atomic mass by 4.
An example is the alpha decay below
¹⁷⁵Pt₇₈ ----> ¹⁷¹ Os₇₆ + ⁴ He₂
Here,Platinum 175 with atomic number 78 undergoes alpha decay to produce Osmium 171 with atomic number 76.
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Aqueous sodium bicarbonate was used to wash the crude n-butyl bromide. a. What was the purpose of this wash? Give equations. b. Why would it be undesirable to wash the crude halide with aqueous sodium hydroxide? 5. Look up the density of n-butyl chloride (1-chlorobutane). Assume that this alkyl halide was prepared instead of the bromide. Decide whether the alkyl chloride would appear as the upper or the lower phase at each stage of the separation procedure: after the reflux, after the addition of water, and after the addition of sodium bicarbonate.
Answer:
See explanation below
Explanation:
a) According to this, this is an excercise that is involving a separation and reaction of different compounds. The n-butyl bromide is formed when, you made the following reaction:
CH2 = CH - CH2 - CH3 + HBr/peroxide -----------> Br - CH2 - CH2 - CH2 - CH3
Now, in this reaction, we still has traces of HBr in the product, so, in order to neutralize these traces, we wash the solution with bicarbonate sodium forming sodium bromide and carbonic acid as follow:
HBr + Na2CO3 ---------> NaBr + Na2CO3
Also, this is a weak base so it will not react with the n-butylbromide to form another product.
b) Basing of what it was stated above, we cannot wash the solution with NaOH because this is a strong base, and not only wil eliminate the traces of HBr, it will also react with the butylbromide causing an elimination and substitution reaction, giving the following products:
BrCH2CH2CH2CH3 + NaOH --->CH2=CHCH2CH3 + OHCH2CH2CH2CH3
That it's why we need to wash this product with a weak base only.
c) The density of 1-chlorobutane is 0.88 g/mL, density of water is 1 g/mL and density of sodium bicarbonate is 2.2 g/cm3, therefore, the one that has a greater density will go at the lower phase.
In this case, after the reflux, it will stay in the lower phase.
after adding water, it will be in the upper phase.
after adding bicarbonate, it will be in the upper phase too.
a. The purpose of washing the crude n-butyl bromide with aqueous sodium bicarbonate is to remove acidic impurities. b. It would be undesirable to wash the crude halide with aqueous sodium hydroxide. After each stage of the separation procedure, the alkyl chloride would appear as the upper or lower phase.
Explanation:a. The purpose of washing the crude n-butyl bromide with aqueous sodium bicarbonate is to remove any acidic impurities. Sodium bicarbonate is a weak base that reacts with acidic impurities, such as hydrochloric acid or sulfuric acid, to form water-soluble salts. The balanced chemical equation for the reaction between sodium bicarbonate and hydrochloric acid is:
NaHCO3 + HCl → NaCl + H2O + CO2
b. It would be undesirable to wash the crude halide with aqueous sodium hydroxide because sodium hydroxide is a strong base that can react with the bromide ion to form sodium bromide, which would not be easily separated from the organic layer.
After the reflux, the alkyl chloride would appear as the upper phase. After the addition of water, the alkyl chloride would still appear as the upper phase. After the addition of sodium bicarbonate, the alkyl chloride would appear as the lower phase.
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How much carbon dioxide in kilograms is produced upon the complete combustion of 29.4 L of propane (approximate contents of one 5-gal tank)? Assume that the density of the liquid propane in the tank is 0.621 g / mL.
Answer:
61kg
Explanation:
Like all other hydrocarbons, the combustion of propane will yield water and carbon iv oxide.
Let’s write a complete and balanced chemical equation for this.
C3H8(g) + 5O2(g) → 3CO2(g) + 4H2O(l)
Now, we first convert the information into a mass.
We know that mass = density * volume
Let’s convert the volume here into ml since density is in mL. It must be remembered that 1000ml = 1L. Hence, 29.4L = 29,400ml
The mass is thus = 0.6921 * 29,400 = 20,347.74g
Now from the balanced equation, we can see that one mole of propane produced 3 moles of carbon iv oxide. This is the theoretical relation.
Let’s now calculate the actual number of moles. The number of moles of propane produced is the mass of propane divided by the molar mass of propane. The molar mass of propane is 3(12) + 8(1) = 36 + 8 = 44g/mol
The number of moles = 20,347.74/44 = 462.44
We simply multiply this number by 3 to get the actual number of moles of carbon dioxide produced. This is equals 1387.35 moles
Since we know this, we now calculate the mass of carbon iv oxide produced. The mass is equals the number of moles multiplied by the molar mass. The molar mass of carbon iv oxide is 44g/mol.
The mass produced is thus 1387.35 * 44 = 61,043g
To get the kilogram equivalent, we simply divide by 1000 = 61,043/1000 = 61kg
Draw the structure of the starting material needed to make 2-methylhept-3-yne using sodium amide in liquid ammonia
Answer:
3,4-dibromo 2-methylheptane
Explanation:
Alkynes can be synthesized by using sodium amide in liquid ammonia, when the starting material is a vicinal dibromoalkane. This means an alkane in which there's a Br group in two carbons next to one another.
In the attached picture you can see the reaction.
Answer:
see picture
Explanation:
Although the previous answer may be correct, the question is incomplete, the completed question is:
Draw the structure of the starting material needed to make 2-methylhept-3-yne using sodium amide in liquid ammonia followed by 1-bromopropane.
Now, the previous answer is also incorrect, because the starting material with the two bromine in carbon 3 and 4, the first reaction taking place is the substracting of the hydrogen from carbon 5, and not carbon 3 because it's bulkier than carbon 5. So the majority product formed will be a double bonded product and not a triple bond. Therefore, this answer is incorrect.
Now, that we have completed the question the Starting material would have to be the following:
CH3 - CH(CH3) - C ≡ CH
When this reactant, is in presence of NaNH2, the NH2 substract the Hydrogen from carbon 1, and then, this will attack as nucleophyle to the carbon 1 of the bromopropane and formed the desired product.
The mechanism is as following in the picture.
In which sample of water do the molecules have the highest average kinetic energy 1)20. ML at 100.°C 2)40. ML at 80. °C 3)60. ML at 60.° C 4)80. Ml at 40.° C
Answer:
1)20. ML at 100.°C
Explanation:
Average kinetic energy is not related with volume. so increase in temperature will also increase kinetic energy. so this increase means the highest temperature will be a right answer.
Final answer:
The water sample with the highest average kinetic energy is the 20 mL of water at 100.0°C, as average kinetic energy is directly proportional to temperature.
Explanation:
The molecules with the highest average kinetic energy are in the sample of water at the highest temperature. Kinetic energy is directly proportional to the absolute temperature of the substance, meaning that as temperature increases, kinetic energy also increases. Therefore, ignoring the volume of the water samples, the rank from highest kinetic energy to lowest based on temperature would be:
20 mL of water at 100.0°C40 mL of water at 80.0°C60 mL of water at 60.0°C80 mL of water at 40.0°CThe sample at 100.0°C holds the highest average kinetic energy because it has the highest temperature.
A compound is 7.74% hydrogen and 92.26% carbon by mass. At 100°C a 0.6883 g sample of the gas occupies 250 mL when the pressure is 820 torr. What is the molecular formula for this compound?
Answer: The molecular formula for the compound is [tex]C_6H_6[/tex]
Explanation:
We are given:
Percentage of C = 92.26 %
Percentage of H = 7.74 %
Let the mass of compound be 100 g. So, percentages given are taken as mass.
Mass of C = 92.26 g
Mass of H = 7.74 g
To formulate the empirical formula, we need to follow some steps:
Step 1: Converting the given masses into moles.Moles of Carbon =[tex]\frac{\text{Given mass of Carbon}}{\text{Molar mass of Carbon}}=\frac{92.26g}{12g/mole}=7.68moles[/tex]
Moles of Hydrogen = [tex]\frac{\text{Given mass of Hydrogen}}{\text{Molar mass of Hydrogen}}=\frac{7.74g}{1g/mole}=7.74moles[/tex]
Step 2: Calculating the mole ratio of the given elements.For the mole ratio, we divide each value of the moles by the smallest number of moles calculated which is 7.68 moles.
For Carbon = [tex]\frac{7.68}{7.68}=1[/tex]
For Hydrogen = [tex]\frac{7.74}{7.68}=1[/tex]
Step 3: Taking the mole ratio as their subscripts.The ratio of C : H = 1 : 1
The empirical formula for the given compound is [tex]CH[/tex]
Calculating the molar mass of the compound:To calculate the molecular mass, we use the equation given by ideal gas equation:
PV = nRT
Or,
[tex]PV=\frac{m}{M}RT[/tex]
where,
P = pressure of the gas = 820 torr
V = Volume of gas = 250 mL = 0.250 L (Conversion factor: 1 L = 1000 mL )
m = mass of gas = 0.6883 g
M = Molar mass of gas = ?
R = Gas constant = [tex]62.3637\text{ L. torr }mol^{-1}K^{-1}[/tex]
T = temperature of the gas = [tex]100^oC=(100+273)K=373K[/tex]
Putting values in above equation, we get:
[tex]820torr\times 0.250L=\frac{0.6883g}{M}\times 62.3637\text{ L torr }mol^{-1}K^{-1}\times 373K\\\\M=\frac{0.6883\times 62.3637\times 373}{820\times 0.250}=78.10g/mol[/tex]
For determining the molecular formula, we need to determine the valency which is multiplied by each element to get the molecular formula.
The equation used to calculate the valency is:
[tex]n=\frac{\text{Molecular mass}}{\text{Empirical mass}}[/tex]
We are given:
Mass of molecular formula = 78.10 g/mol
Mass of empirical formula = 13 g/mol
Putting values in above equation, we get:
[tex]n=\frac{78.10g/mol}{13g/mol}=6[/tex]
Multiplying this valency by the subscript of every element of empirical formula, we get:
[tex]C_{(1\times 6)}H_{(1\times 6)}=C_6H_6[/tex]
Hence, the molecular formula for the compound is [tex]C_6H_6[/tex]
The pH pH scale for acidity is defined by pH = − log 10 [ H + ] pH=-log10[H+] where [ H + ] [H+]is the concentration of hydrogen ions measured in moles per liter (M). A solution has a pH pH of 4.6. Calculate the concentration of hydrogen ions in moles per liter (M). The concentration of hydrogen ions is Preview moles per liter.
Answer:
2 51 × 10^-5mol/L
Explanation:
The concentration of hydrogen ions can be calculated using the formula below :
pH = -log [H+]
pH = 4.6
[H+] = ?
[H+] = Antilog (-4.6)
[H+] = 2 51 × 10^-5mol/L
On Earth, the white colored paper represents areas that are A) covered with snow and reflect sunlight. B) heavily populated and use the sunlight. Eliminate C) covered with water and reflect sunlight. D) covered with concrete and absorb sunlight.
In an ecosystem model of earth , white colored paper represents areas that are covered with snow and reflect sunlight.
What is an ecosystem?Ecosystem is defined as a system which consists of all living organisms and the physical components with which the living beings interact. The abiotic and biotic components are linked to each other through nutrient cycles and flow of energy.
Energy enters the system through the process of photosynthesis .Animals play an important role in transfer of energy as they feed on each other.As a result of this transfer of matter and energy takes place through the system .Living organisms also influence the quantity of biomass present.By decomposition of dead plants and animals by microbes nutrients are released back in to the soil.
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Dalton's experiments advanced our understanding of the atom withoutA.carefully observing and measuring events.B.discovering the internal structure of the atom.C.examining the ratios of elements involved in chemical reactions.D.testing a hypothesis.
Answer:
B: Discovering the internal structure of the atom.
Explanation:
Dalton’s experiments with gases marked the beginning of the modern era of chemistry. The hypotheses about the nature of matter on which Dalton’s atomic theory is based can be
summarized as follows:
Elements are composed of extremely small particles called atoms. All atoms of a given element are identical, having the same size, mass, and chemical properties. The atoms of one element are different from the atoms of all other elements. Compounds are composed of atoms of more than one element. In any compound, the ratio of the numbers of atoms of any two of the elements present is either an integer or a simple fraction. A chemical reaction involves only the separation, combination, or rearrangement of atoms; it does not result in their creation or destruction.Dalton made no attempt to describe the structure or composition of atom —he had no idea what an atom is really like. But he did realize that the different properties shown by elements such as hydrogen and oxygen can be explained by assuming that hydrogen atoms are not the same as oxygen atoms.
Which combination of elements will form an ionic bond?
A.) sodium and calcium
B.) nitrogen and helium
C.) potassium and chlorine
D.) oxygen and fluorine
Answer:
The correct answer is option C.
Explanation:
Ionic bond is defined as the bond which is formed by complete transfer of electrons from one atom to another atom.
The atom which looses the electron is known as electropositive atom and the atom which gains the electron is known as electronegative atom. This bond is usually formed between a metal and a non-metal.Ionic compound is formed by the complete transfer of electrons from 1 atom to another atom. The cation is formed by the loss of electrons by metals and anions are formed by gain of electrons by non metals.
From the given options , the option with metal and non metal is potassium and chlorine. these elements will combine together to form ionic compound called potassium chloride.
To determine the moles of ammonium chloride produced, we need to find the limiting reactant. H2O is present in an unlimited amount, so it cannot be the limiting reactant. Let’s then determine the amount of each remaining reactant present (in moles). NaCl is already given in moles (0.250 mol). NH3 and CO2 are not. They are given in liters. How many moles are present in 3.08 L of NH3 and 2.09 L of CO2?
Answer:
0.094 mols of CO2 are present in 2.09 L.
0.132 mols of NH3 are present in 3.08 L
The moles of ammonium chloride produced are 0.094
Explanation:
First of all, think the reaction
NH3 + 2H2O + NaCl + CO2 → NH4Cl + NaOH + H2CO3
To get the moles with volume, you must need density
Density = mass / volume
Density CO2 = 0,001976 g/ml
Density NH3 = 0,00073 g/ml
Volume of CO2 = 2.09L
2.09 L . 1000 = 2090 mL
0,001976 g/ml = mass / 2090 mL
4.13 g = mass
Molar weight = 44 g/m
mass / molar weight = 4.13 g / 44 g/m = 0.094 moles
Volume of NH3 = 3.08 L
3.08 L . 1000 = 3080 mL
0,00073 g/ml = mass/ 3080 mL
2.25 g = mass
Molar weight = 17 g/m
mass / molar weight = mols → 2.25 g / 17g/m = 0.132 mols
In my reagents, the least amount I have is CO2. This is my limiting reactant. Take account the reaction.
1 mol of NH3 reacts with 1 mol of CO2, so as I have 0.132 moles of NH3 I need 0.132 moles of CO2; I only have 0.094.
Relation between CO2 and NH4Cl is 1:1 so, 1 mol of CO2 is needed to produce 1 mol e chloride, so 0.094 mols are needed to produce the same amount of chloride.
Hydrogen gas produced in the laboratory by the reaction of zinc and hydrochloric acid was 23) collected over water at 25°C. The barometric pressure at the time was 742.5 mm Hg. What is the pressure of dry hydrogen gas if the vapor pressure of water at 25'C is 23.8 mm Hg?
A) 760.0 mm Hg
B)718.7 mm Hg
C)742.5 mm Hg
D) 766.3 mm Hg
E) none of the above
Answer:
Explanation:
The balanced chemical reaction is:
[tex]Zn+2HCl\rightarrow ZnCl_2+H_2[/tex]
According to Dalton's law, the total pressure is the sum of individual pressures.
[tex]p_{total}=p_1+p_2[/tex]
As the hydrogen is collected over water, the total pressure will be sum of pressure of water and pressure of dry hydrogen.
[tex]p_{total}=p_{H_2}+p_{H_2O}[/tex]
[tex]p_{total}[/tex] = 742.5 mm Hg
[tex]p_{H_2}[/tex] = ?
[tex]p_{H_2O}[/tex] = 23.8 mm Hg
Putting in the values:
[tex]742.5=p_{H_2}+23.8[/tex]
[tex]742.5-23.8=p_{H_2}[/tex]
[tex]p_{H_2}=718.7mmHg[/tex]
Thus the pressure of dry hydrogen gas is 718.7 mm Hg
Which elements have the most similar chemical properties
Final answer:
Elements within the same group or family on the periodic table have the most similar chemical properties due to their identical number of valence electrons. Examples include alkali metals such as lithium and sodium, and halogens like fluorine and chlorine.
Explanation:
Elements that have the most similar chemical properties are typically found within the same group on the periodic table. Groups, also known as families, contain elements with the same number of valence electrons. For example, the alkali metals such as lithium (Li) and sodium (Na) have one valence electron, making them highly reactive and sharing similar chemical behaviors like forming compounds with oxygen in a 2:1 ratio.
Similarly, alkaline earth metals like beryllium (Be) and magnesium (Mg) each have two valence electrons and also show close chemical properties. The halogens—including fluorine (F) and chlorine (Cl)—each have seven valence electrons, leading to their characteristic reactivity and ability to form compounds with elements such as sodium.
As elements share the same number of valence electrons, it leads to similarities in the ways they lose, gain, or share electrons during chemical reactions. The patterns of chemical properties extend beyond single groups; for instance, metallic character increases as one moves down a group in the periodic table.
A .115 L sample of dry air has a pressure of 1.0895633 atm at 377 K. What is the volume of the sample if the temperature is increased to 483 K when the pressure is kept constant?
Answer:
V= 0.147 L
Explanation:
This is simply the application of combined gas law twice, to find the unknowns.
Combined gas law states that: [tex]PV = nRT[/tex]
P= pressure of air
V= volume of air
n= moles of air
R= Universal gas constant ( 0.08205 L atm mol⁻¹ K⁻¹)
T= Absolute temperature in kelvin.
[tex]n=\frac{P * 0.115}{R * 377}[/tex]
Now, applying the same gas law at 483K and substituting for n
[tex]V = \frac{P * 0.115}{R * 377} * \frac{R* 483}{P}[/tex]
V= [tex]\frac{0.115 * 483}{377}[/tex]
V= 0.147 L
Consider the reaction CH4(g) + X2(g) → CH3X(g) + HX(g), where X is a halogen-like atom (Group 7A). Calculate ∆H for this reaction if bond energy tables give the following values: C H : 416 kJ/mol X X : 230 kJ/mol H X : 277 kJ/mol C X : 222 kJ/mol Answer in units of kJ/mol.
Answer:
ΔH of reaction is -147 kJ/mol
Explanation:
For the reaction:
CH₄(g) + X₂(g) → CH₃X(g) + HX(g)
It is possible to obtain ΔHr of reaction from the sum of ΔH of products minus ΔH of reactants:
ΔHr = ΔH CH₃X + ΔH HX - (ΔH CH₄ + ΔH X₂) (1)
The ΔH of each compound is obtained from bond energies thus:
ΔH CH₃X = 3×C-H + C-X = 3×416 kJ/mol + 222 kJ/mol = 1470 kJ/mol
ΔH HX = H-X = 277 kJ/mol
ΔH CH₄ = 4×C-H = 4×416kJ/mol = 1664 kJ/mol
ΔH X₂ = X-X = 230 kJ/mol
Replacing in (1):
ΔHr = 1470 kJ/mol + 277kJ/mol - (1664 kJ/mol + 230 kJ/mol) = -147 kJ/mol
I hope it helps!
Final answer:
To calculate the enthalpy change for CH₄ + X₂ → CH₃X + HX, we tally the energy needed to break one C-H bond and one X-X bond (total 646 kJ/mol) and subtract the energy released from forming one C-X bond and one H-X bond (total 499 kJ/mol), resulting in a ΔH of 147 kJ/mol.
Explanation:
To calculate the enthalpy change (ΔH) for the reaction CH₄(g) + X₂(g) → CH₃X(g) + HX(g), we need to consider the bond energies provided. The calculation involves computing the energy required to break bonds in the reactants and the energy released from forming bonds in the products.
First, we break one C-H bond in CH₄ and one X-X bond. The energy required is:
1 mol C-H: 416 kJ/mol
1 mol X-X: 230 kJ/mol
When these connections are broken, the total energy needed is:
416 kJ/mol + 230 kJ/mol = 646 kJ/mol
Next, we form one C-X bond and one H-X bond with the energies released as follows:
1 mol C-X: 222 kJ/mol
1 mol H-X: 277 kJ/mol
The total energy released in forming these bonds is:
222 kJ/mol + 277 kJ/mol = 499 kJ/mol
The enthalpy change of the reaction is the energy required minus the energy released:
ΔH = 646 kJ/mol - 499 kJ/mol = 147 kJ/mol
This reaction is endothermic, as indicated by the positive value of ΔH.
Redox reactions can be written as two half-reactions, focusing on the gain or loss of electrons by one of the chemical substances. One half-reaction shows the oxidation while the other shows the reduction. When the two half-reactions are combined, the overall reaction is obtained.The half-reactions can aid in the balancing of redox equations because the number of each element must be balanced as well as the number of electrons gained and lost. What substance is added to balance the hydrogen in a half-reaction?
A. H₂O₂
B. H₂O
C. H⁺
D. H₂
Answer:
C) H⁺
Explanation:
When we are balancing the reaction in an acid medium, hydrogen is balanced using the H⁺ species. This is most likely the intended answer of your question.
When the reaction takes place not in an acid medium, but in an alkaline one, then hydrogen is present as the OH⁻ species. However this option is not given in your question.
Thus the answer is option C).
Which of the following processes is endothermic?A. a hot cup of soup (system) cools on a countertop B. the combustion of butaneC. the chemical reaction in a "hot pack" often used to treat sore musclesD. the vaporization of rubbing alcohol E. the freezing of water
Answer: Option (D) is the correct answer.
Explanation:
A reaction in which heat energy is absorbed by the molecules of a substance is known as an endothermic reaction.
Whereas when energy is released by the molecules of a substance in a reaction then it is known as an exothermic reaction.
So, when a hot cup of soup (system) cools on a countertop then energy is released into the surrounding by the soup. Hence, it is an exothermic reaction.Also, combustion reactions are always exothermic in nature.The chemical reaction in a "hot pack" often used to treat sore muscles because heat is released to the muscles. Therefore, it is an exothermic reaction.When rubbing alcohol vaporizes then heat is absorbed by the molecules of alcohol. Due to which they gain energy and escape into the surrounding. Therefore, it is an endothermic reaction.Freezing of water is an exothermic reaction because during this process energy is released by the molecules of water. Hence, it is an exothermic reaction.Thus, we can conclude that the vaporization of rubbing alcohol is endothermic.
Among the provided options, the vaporization of rubbing alcohol is the endothermic process, as it involves the absorption of heat from its surroundings.
Explanation:In the context of chemistry, an endothermic process is one in which heat is absorbed from the surroundings. This results in an overall increase in the internal energy of the system. Given the options, the vaporization of rubbing alcohol is the process that is endothermic. This is because when rubbing alcohol vaporizes, it absorbs heat from its surroundings, causing the surrounding environment to feel cooler. Other examples might be the melting of ice or the evaporation of water, both of which require an external heat source to facilitate the process.
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When 100 ml of 1.0 M Na3PO4 is mixed with 100 ml of 1.0 M AgNO3,
a yellow precipitate forms and Ag+ becomes negligibly small. Which
of the following is the correct listing of the ions remaining in solution
in order of increasing concentration?
(A) PO43- < NO3- < Na+
(B) PO43- < Na+ < NO3-
(C) NO3- < PO43- < Na+
(D) Na+ < NO3- < PO43-
(E) Na+ < PO43- < NO3-
Answer:
[tex]PO_4^{-3} < NO_3^- < Na^+[/tex]
Explanation:
Solutions.
a) 100 ml 1 M of Na3PO4
b) 100 ml 1 M of AgNO3
c) Mixture: 200 ml 0.5 M of Na3PO4 and 0.5 M of AgNO3
Reaction:
[tex] 3 Ag^+ + PO_4^{-3} \longrightarrow Ag_3PO_4[/tex]
So if silver ion is consumed almost completely:
[tex][Ag^+]=0 M[/tex]
[tex][PO_4^{-3}]=0.5 M-0.5 M \frac{1 mol PO4}{3 mol Ag}=0.33 M[/tex]
[tex][Na^+]=0.5 M * \frac{3 mol Na}{mol Na_3PO_4}=1.5 M[/tex]
[tex][NO_3^-]=0.5 M[/tex]
In increasing order of concentration:
[tex]PO_4^{-3} < NO_3^- < Na^+[/tex]
The correct order of ions remaining in solution after mixing Na3PO4 with AgNO3, by increasing concentration, is phosphate (PO43-), nitrate (NO3-), and sodium (Na+), which is option (A).
Explanation:When 100 ml of 1.0 M Na3PO4 is mixed with 100 ml of 1.0 M AgNO3, a reaction occurs where silver phosphate (Ag3PO4), a yellow precipitate, forms due to its low solubility and Ag+ ions become almost absent in the solution. The remaining ions in the solution will be Na+, NO3-, and a very small amount of PO43-. Since all of the Ag+ reacts to form the precipitate, we can assume that there are three times as many Na+ ions compared to PO43- ions originally, because each formula unit of Na3PO4 produces three sodium ions. Therefore, this leaves Na+ with the highest concentration in solution. NO3- concentration remains unchanged because it is a spectator ion and does not participate in the reaction.
The correct order of ions in solution by increasing concentration is PO43- < NO3- < Na+, which corresponds to option (A).
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The charge of B is +3 and the charge of O is -2. What is its formula?
A) B3O2
B) B2O3
C) O2B3
A quantity of N2 gas originally held at 5.23 atm pressure in a 1.20 −L container at 26 ∘C is transferred to a 14.5 −L container at 20 ∘C. A quantity of O2 gas originally at 5.21 atm and 26 ∘C in a 5.10 −L container is transferred to this same container.
To find the final pressure of the gas mixture after transferring the gases, we can use the ideal gas law equation. The final pressure is calculated based on the total number of moles of gas and the final volume of the container. The final pressure of the gas mixture is 0.229 atm.
Explanation:To find the final pressure of the gas mixture after the transfer, we can use the ideal gas law equation, which states that PV = nRT, where P is the pressure, V is the volume, n is the number of moles, R is the ideal gas constant, and T is the temperature.
We can calculate the number of moles of N2 gas using the information given:
n = PV/RT = (5.23 atm)(1.20 L)/(0.0821 atm·L/mol·K)(26 + 273 K) = 0.287 mol
Similarly, we can calculate the number of moles of O2 gas:
n = PV/RT = (5.21 atm)(5.10 L)/(0.0821 atm·L/mol·K)(26 + 273 K) = 1.05 mol
To find the final pressure, we need to find the total number of moles of gas and the final volume of the container:
Total moles of gas = moles of N2 + moles of O2 = 0.287 mol + 1.05 mol = 1.34 mol
Final volume of the container = sum of the initial volumes = 1.20 L + 14.5 L = 15.7 L
Now we can use the ideal gas law again to calculate the final pressure:
P = nRT/V = (1.34 mol)(0.0821 atm·L/mol·K)(20 + 273 K)/(15.7 L) = 0.229 atm
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For the question that follow, consider the BEST Lewis structures of the following oxyanions:
(i) NO2 -
(ii) NO3 -
(iii) SO3 2-
(iv) SO4 2-
(v) BrO3 -
In which of the ions do all X-O bonds (X indicates the central atom) have the same length?
In Lewis structures, all X-O bonds have the same length in NO3 -, SO4 2-, and BrO3 -. This is due to resonance, whereby the electron density is distributed among multiple equivalent structures.
Explanation:In the Lewis structures of the given oxyanions, the ions in which all X-O bonds have the same length are: (ii) NO3 -, (iv) SO4 2-, and (v) BrO3 -. The concept of bond length in these ions is connected to the principle of resonance. Each of these ions exhibit resonance, which means the electron density is distributed among more than one equivalent Lewis structures. This leads to the bonds having the same length. For example, in the SO4 2- ion, there are multiple resonance structures, each involving double bonds between the sulfur and the different oxygen atoms. As these double bonds can 'move' about the ion (due toan resonce), the four sulfur-oxygen bonds are of equal length. Such a phenomenon is not present in (i) NO2 - and (iii) SO3 2-.
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Final answer:
The NO2- ion has all X-O bonds with the same length.
Explanation:
The Lewis structure of an ion represents the arrangement of atoms and electrons in the ion.
In the oxyanions provided, only NO2- has all X-O bonds (X representing the central atom) with the same length.
This is because the NO2- ion has resonance structures, which means the double bond can be located between either of the two oxygen atoms. As a result, the N-O bonds in NO2- are identical in length.
What is the full name of NI3
Answer:
Nitrogen triiodide is NI3.
Explanation:
Given that Δ H ∘ f [ Br ( g ) ] = 111.9 kJ ⋅ mol − 1 Δ H ∘ f [ C ( g ) ] = 716.7 kJ ⋅ mol − 1 Δ H ∘ f [ CBr 4 ( g ) ] = 29.4 kJ ⋅ mol − 1 calculate the average molar bond enthalpy of the carbon‑bromine bond in a CBr 4 molecule.
Answer:
283.725 kJ ⋅ mol − 1
Explanation:
C(s) + 2Br2(g) ⇒ CBr4(g) , Δ H ∘ = 29.4 kJ ⋅ mol − 1
[tex]\frac{1}{2}[/tex]Br2(g) ⇒ Br(g) , Δ H ∘ = 111.9 kJ ⋅ mol − 1
C(s) ⇒ C(g) , Δ H ∘ = 716.7 kJ ⋅ mol − 1
4*eqn(2) + eqn(3) ⇒ 2Br2(g) + C(s) ⇒ 4 Br(g) + C(g) , Δ H ∘ = 1164.3 kJ ⋅ mol − 1
eqn(1) - eqn(4) ⇒ 4 Br(g) + C(g) ⇒ CBr4(g) , Δ H ∘ = -1134.9 kJ ⋅ mol − 1
so,
average bond enthalpy is [tex]\frac{1134.9}{4}[/tex] = 283.725 kJ ⋅ mol − 1
The average molar bond enthalpy of the carbon‑bromine bond in a CBr 4 molecule is 283.725 kJ ⋅ mol − 1
Calculation of average molar bond:C(s) + 2Br2(g) ⇒ CBr4(g) , Δ H ∘ = 29.4 kJ ⋅ mol − 1
Br2(g) ⇒ Br(g) , Δ H ∘ = 111.9 kJ ⋅ mol − 1
C(s) ⇒ C(g) , Δ H ∘ = 716.7 kJ ⋅ mol − 1
4*eqn(2) + eqn(3)
⇒ 2Br2(g) + C(s)
⇒ 4 Br(g) + C(g) , Δ H ∘
= 1164.3 kJ ⋅ mol − 1
eqn(1) - eqn(4)
⇒ 4 Br(g) + C(g)
⇒ CBr4(g) , Δ H ∘
= -1134.9 kJ ⋅ mol − 1
so,
average bond enthalpy is = 283.725 kJ ⋅ mol − 1
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Consider the following reduction potentials:
2H+ + 2e– → H2 E° = 0.00 V Ni2+ + 2e– → Ni E° = -0.25 V Cd2+ + 2e– → Cd E° = -0.40 V
Based on this information which pairs of substances will react spontaneously under standard state conditions?
Answer:
H⁺/H₂//Ni/Ni⁺²; H⁺/H₂//Cd/Cd⁺²; Ni⁺²/Ni//Cd/Cd⁺²
Explanation:
The redox reactions are spontaneously when the E° of the substance that is reduced is higher than the E° of the substance that is oxidized. The substance is reduced when gaining electrons and is oxidized when loses electrons.
So, the reactions that occur spontaneously are:
2H⁺ + Ni → H₂ + Ni⁺² (H⁺ is reduced and Ni is oxidized)
2H⁺ + Cd → H₂ + Cd⁺² (H⁺ is reduced and Cd is oxidized)
Ni⁺² + Cd → Ni + Cd⁺² (Ni⁺² is reduced and Cd is oxidized)
Pairs: H⁺/H₂//Ni/Ni⁺²; H⁺/H₂//Cd/Cd⁺²; Ni⁺²/Ni//Cd/Cd⁺²
A researcher is performing a gram stain on a specimen in a medical laboratory. She gets distracted by a phone call and accidentally uses water instead of alcohol to decolorize. What may happen as a result of this mistake?
Answer:
Explanation:
It wouldn't be able to separate negative gram from positive. it would not wash away some of the crystal violet stain effectively. Gram - Cells will appear to be the same hue. Water can also dilute cells or wash them off the slide
Answer:
Explanation:
Would not be able to differentiate gram - from + it would not efficiently wash some of the crystal violet stain away. gram - cells will still remain the same color. also water may dilute or wash cells off the slide
The atomic number of an element is the same as the number of its
Answer: The atomic number of an element is the same as the number of its protons.
Explanation: For example, the atomic number of oxygen is 8. So, this would mean that the number of protons would be 8.
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What type of compound is held together w/ electrostatic forces?
Answer:
Ionic compound.
Explanation:
Ionic bond:
It is the bond which is formed by the transfer of electron from one atom to the atom of another element. the electrostatic attraction is created between bonded atoms.
Both bonded atoms have very large electronegativity difference. The atom with large electronegativity value accept the electron from other with smaller value of electronegativity.
The compound having ionic bonds generally have moderate to high boiling points and melting point because of greater electrostatic interaction. Their electrical conductivity are high and these minerals tend to dissolve in water.
For example:
Sodium chloride is ionic compound. The electronegativity of chlorine is 3.16 and for sodium is 0.93. There is large difference is present. That's why electron from sodium is transfer to the chlorine. Sodium becomes positive and chlorine becomes negative ion and both atoms joint together through electrostatic interaction.
An unknown diatomic gas has a density of 3.164 g/l at stp. What is the identity of the gas?
Answer:
The identity of the gas is Cl₂ (chlorine)
Explanation:
STP conditions are:
1 atm → Pressure
273.15 K → T°
So, we must use the Ideal Gas Law to get the moles.
Before that, we will think density as data where 3.164 g of diatomic gas are contained in 1 L of volume.
P.V = n . R . T
1 atm . 1 L = n. 0.082 L.atm/mol.K . 273.15K
1 L.atm / (0.082 L.atm/mol.K . 273.15K) = n
0.0446 mol = n
This quantity of diatomic gas, are 3.164 g so the molar mass will be:
Mass / mol = molar mass
3.164 g / 0.0446 mol = 70.9 g/m
The element (a diatomic molecule), which has that molar mass in the periodic table is the Cl₂.
1 Cl = 35.45 g/m
Cl₂. = 70.9 g/m
Using the density data and Avogadro's principle, we can calculate the molar mass of the unknown gas to be around 70.8 g/mole. Yet, none of the gases from the provided list align with this molar mass.
Explanation:The identity of the unknown diatomic gas can be found using the Ideal Gas Law and Avogadro's principle. Avogadro's principle states that equal volumes of gases at the same temperature and pressure will contain an equal number of particles (or moles). Hence, at Standard Temperature and Pressure (STP), 1 mole of any gas will occupy 22.4 L.
From the data provided, we know that 1 mole of the unknown gas has a mass of 3.164 g/L × 22.4 L per mole = 70.8 g/mole. Among the different potential gases listed in the reference, O₂ is a diatomic gas and has a molar mass of 32g/mole, which isn't close to the calculated one. NH3 has a molar mass of 17g/mole which also doesn't match. This leaves us with He (Helium), which is not diatomic and hence can't be our gas. We can therefore confidently conclude that there seems to be a mistake as none of the gases listed align with our calculated molar mass.
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What is meant by the mass percent concentration of a solution
Answer:
The mass of a solute divided by the mass of a solution times 100
Explanation:
The concentration of a solution refers to how much of a solute is dissolved in an amount of solvent. To express this concentration exist different methods, the mass percent concentration is one of them and is defined as the mass of a solute divided by the mass of a solution times 100:
%m/m= (mass of a solute/mass of solution)x100
Where the mass of the solution is the sum of the mass of solute and mass of solvent.
%m/m is commonly used when you can measure the masses of both solute and solution.
I hope you find this information useful and interesting! Good luck!
Mass percent in chemistry denotes the proportion of a solute in a solution in terms of a percentage. It's calculated as: Mass Percent = (mass of solute/mass of solution) * 100.
Explanation:The mass percent concentration of a solution signifies the proportion of a solute in a certain quantity of solution, and it is displayed as a percentage. To calculate the mass percent, we use the formula:
Mass Percent = (mass of solute/mass of solution) * 100
If, for example, you have a solution composed of 20g of sugar in 180g of water, the mass of the solution would be the sum of these two (200g), and thus the mass percent of sugar in the solution is (20/200)*100 = 10%.
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According to Newton�s first law of motion, if there is no net force (unbalanced forces) acting on an object that is moving at a constant 30 mph, the object will:
Continue to move at 30 mph
Eventually come to a stop
Change its inertia
Accelerate
Answer:
Continue to move at 30 mphExplanation:
Newton's first law of motion :
"Every object persists in its state of rest or uniform motion in a straight line unless it is compelled to change that state by forces exerted on it."
From the question we know that the net forces on the object were zero or that the there were no unbalanced forces on it.
Therefore we can assume that the object is moving along a straight line.
And the object was moving at a constant speed of 30 mph.
So it is clear from the Newton's first law that the object will remain in the state of motion as it was earlier.
That is the object will remain in motion at constant speed of 30 mph.
At what ph did you see the highest activity of salivary amylase
Answer: highest activity of salivary amylase is at pH 6.8.
Explanation:Amylase enzyme catalyses the hydrolysis of starch into sugars. Amylase is present in the saliva of humans and some other mammals. The enzymatic activity of salivary amylase ranges from 6 to 7. Above and below this range, the reaction rate reduces as enzymes get denaturated. But the optimum enzymatic activity is at pH 6.8.