The energy changes in two partial reactions are 225.3 kJ
and -432.0 kJ. The combined reaction is exothermic.
The combined reaction is exothermic , with the heat of reaction as -206.7 kJ
What is an Exothermic Reaction ?A reaction in which energy is liberated when reactants react to form products , The energy level of the reactant is more than that of the products.
The energy is liberated in the form of heat.
In the question it is given that
The energy changes in two partial reactions are 225.3 kJ and -432.0 kJ
The combined reaction is exothermic.
For the reaction to be exothermic the value of the heat of the reaction must be negative.
Summing the two energy changes will give us the heat of the combined reaction.
225.3 - 432.0
= -206.7 kJ
The combined reaction is exothermic , with the heat of reaction as -206.7 kJ.
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A student made a graph plotting the progress of a reaction over time. The student forgot to label the y-axis of the graph.
A graph is shown with two graph lines. One graph line starts at a higher position on the y axis and slopes downwards towards the right. The other graph line starts at a lower position on the y axis and slopes upwards towards the right. The two graph lines stop short of intersecting each other and continue as separate lines which gradually become straight and parallel to the x axis. A vertical line is shown at a point where the two graph lines finally became parallel to the x axis. This vertical line is labeled equilibrium. The title on the x axis is Time and an arrow pointing towards the right is shown above Time. The title on the y axis is left blank.
What best explains the label that the student should use on the y-axis? (5 points)
Group of answer choices
Amount, because as the amount of product decreases, the amount of reactant increases over time.
Reaction rate, because forward and backward reaction become equal at equilibrium.
Amount, because the amounts of reactants and products become constant after equilibrium is reached.
Reaction rate, as the rate of forward reaction increases and rate of backward reaction decreases over time.
Answer:
C
Explanation:
Recall that, at equilibrium, the concentration of the reactants and products stop changing because both the forward and reverse reaction rates are equal.
Therefore, Choice C is correct.
Choice A is incorrect because there is no indication that the upper line describes the products and the lower line describes the reactants.
Choice B is incorrect because the statement, while true, is not reflected by the graph. (The two lines after equilibrium are not at the same y-value.)
Choice D is incorrect because the forward reaction rate generally decreases as time increases due to the decrease in reactant concentration(s).
a gas measures 725mm and 32C. what will be the temperature of the gas at 705mm?
Answer:
31°C
Explanation:
Using the ratio, we can find the temperature of the gas at 705mm.
725mm : 32°C
705mm : x
[ x is the temperature we have to find ]
Cross multiply the ratios.
725x = 705 × 32
725x = 22560
x = [tex]\frac{22560}{725}[/tex] = 31°C
59:27
Heat that flows by conduction is the transfer of thermal energy between substances in contact. What must occur for
this to happen?
O The two systems must be the same temperature.
The two systems must not be touching each another.
O One system must have higher kinetic energy than the other system.
O The thermal energy of one system must be the same as the thermal energy of the other system.
Answer:
O One system must have higher kinetic energy than the other system.
Explanation:
Higher KE of the system means hotter......the hotter will transfer heat to the cooler by conduction when they are in contact.
Which of the following is the conjugate base of H3PO4?
2-
OA. HPO4²-
3-
O B. PO4³-
O C. H₂PO4
O D. H₂PO4+
Answer:
H2 PO4 -1 is the correct answer
An acid and a base which differ from each other by a proton are said to form a conjugate pair. Here the conjugate base of H₃PO₄ is H₂PO₄⁻. The correct option is C.
What is a conjugate base?The entity produced when acid gives up a proton has a tendency to regain the proton and hence it behaves as a base. It is called the conjugate base of the parent acid. A base is a substance which acts as a proton acceptor.
Here the conjugate base of H₃PO₄ is formed when a proton is lost from it. So the lose of one proton forms the molecule H₂PO₄⁻ which is the conjugate base. An acid is a proton donor.
When a base accepts a proton it has a tendency to donate the proton and hence behaves as an acid. It is called the conjugate acid of the parent base.
Thus the correct option is C.
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2. Calculate the mass, in grams, for 3.47 moles of each of the following:
a. lead(II) acetate
b. sodium chloride
Explanation:
1 moles Lead(II) Acetate to grams = 325.28804 grams
3.47 moles Lead(II) Acetate to grams = 325.28804 ×3.47 grams=1128.749 grams
1 moles sodium chloride to grams=58.5 grams
3.47 moles sodium chloride to grams=58.5×3.47 grams
=202.995 grams
What do the little numbers (subscripts) next to the lower right of each letter mean in the C₂H₄O₂?
Answer:
It represents the number of atoms of that particular element present in the compound. In C₂H₄O₂ there are 2 Carbon atoms, 4 Hydrogen atoms and 2 Oxygen atoms.
Chemical equation of isopropyl alcohol and ethanoic acid
Answer:
chemical formula of isopropyl alcohol can also be written as: C3H7OH, CH3CHOHCH3 or (CH3)2CHOH.
chemical formula of ethanoic acid is CH₃COOH.
Calculate the volume of 0.10 g of titanium (4.51 g/cm³).
The volume of titanium with mass of 0. 10g and density of 4. 51 g/cm³ is 0. 02 cm³
What is volume?Volume is known to be equal to the mass divided by the density.
It is written thus:
Volume = Mass / density
How to calculate the volumeThe volume is calculated using the formula:
Volume = mass ÷ density
Given the mass = 0. 10g
Density = 4.51 g/cm³
Substitute the values into the formula
Volume of titanium = 0. 10 ÷ 4.51 = 0. 02 cm³
Thus, the volume of titanium with mass of 0. 10g and density of 4. 51 g/cm³ is 0. 02 cm³
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different between effort and load
Answer:
Is that load is a burden; a weight to be carried while effort is the work involved in performing an activity; exertion.Explanation:
mark me as brainlistWhich changes involve forming or breaking chemical bonds?
burning and digesting
boiling and melting
burning and melting
rusting and cutting
Answer: burning and digesting
Both of these are chemical changes.
Answer:
burning and digesting
Explanation:
What is the mass of a cube that has a density of 45g/ml and a volume of 15 ml?
Answer:
675g
Explanation:
The equation that relates mass, density and volume is:
Density = mass ÷ volume
By rearranging the equation we can find the mass of the cube.
Mass = density × volume
Mass = 45 × 15
∴ Mass = 675 grams
Lenses:
reflect light.
can only be concave.
do not have an optical axis.
None of the choices are correct.
Answer:
B. Can only be concave
Explanation:
Statement A is false because lenses do not reflect light. Lenses do have an optical axis.
How is stoichiometry used to calculate energy absorbed when a mass of
liquid boils?
A. Grams liquid x mol/g x A Hreaction
B. Grams liquid x mol/g x A Hvap
OC. Grams liquid x mol/g x AHf
D. Grams liquid x mol/g x AHfusion
Answer: B. Grams liquid x mol/g x A Hvap
Stoichiometry used to calculate energy absorbed when a mass of liquid boils is Grams liquid × mol/g × ΔHvap.
What is Heat of vapourisation?It is the amount of heat evolved when mole of liquid is boiled to form vapours. It is a function of pressure according to which the change will happen in the reaction.
Given is that a particular mass of liquid is boiling.
We have supposed that heat of vapourisation for the same liquid is ΔHvap mol/g. Now if ΔHvap is the heat for 1 mole per gram of the liquid then if the mass of liquid is given,
Energy absorbed can be calculated as = Grams liquid × mol/g × ΔHvap
We should know that when a liquid boils it transforms into gaseous state and the process is called as Vapourisation.
Therefore, Stoichiometry used to calculate energy absorbed when a mass of liquid boils is Grams liquid × mol/g × ΔHvap.
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Calculate the how many sodium atoms must react completely to give 33,6 dm³ hydro-
gen gas at STP.
2Na+ 2H₂O → 2NaOH + H₂(g)
To give 33.6 dm³ hydrogen gas at STP, 18.06 x 10²³ atoms of Na must react completely.
What is Mole concept ?A mole is a unit of measurement used to measure the amount of any fundamental entity (atoms, molecules, ions) present in the substance.
As according to the given equation, 2 moles (ie 12.04 x 10²³ atoms) of Na-atoms produces 1 mole (22.4 ltr) of H₂-gas.
Hence, to produce 33.6 ltr (equivalent to 33.6 dm³) of H₂-gas produced by ;
= 12.04 x 10²³ atoms of Na / 22.4 ltr of H₂-gas x 33.6 ltr
= 18.06 x 10²³ atoms of Na
Hence, To give 33.6 dm³ hydrogen gas at STP, 18.06 x 10²³ atoms of Na must react completely.
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Please help.
Which organic product is formed in the reaction shown in the diagram?
The organic product formed in the reaction shown in the image would be bromoethane.
Substitution reaction in alkanesAlkanes, such as ethane undergoes a substitution reaction with halogens such as bromine to produce haloethanes.
For example, the equation of the reaction between ethane and bromine water is as below:
[tex]C_2H_6 + Br_2 --- > C_2H_5Br + HBr[/tex]
The products formed are bromoethane and hydrobromic acid.
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How can materials be classified on the basis of conduction of heat?
Explanation:
On the basis of electrical conductivity, materials are classified as conductors, semi-conductors and non-conductors. Conductors : Substances through which electricity can easily pass through are known as conductors. For example, copper, silver, mercury etc are good conductors of electricity
What type of reaction is shown below? Check all that apply.
2Mg+O2→2MgO
Answer:
synthesis reaction
Explanation:
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The food you eat can be broken into three main groups: _____, _____, and _____.
1 carbohydrates, fats, and vitamins
2 proteins, fats, and minerals
3 carbohydrates, fats, and proteins
4 proteins, vitamins, and minerals please help :)
Answer:
carbonhydrates, fats and ptoteins
Answer:3 carbohydrates, fats, and proteins
Explanation:
Name one similarity and one difference between visible light and sound.
Answer:
Light and sound both are waves, but sound requires a material medium to travel, and hence cannot travel in empty space while light can travel through vacuum but not through opaque materials. Both undergo refraction, diffraction and interference.
Explanation:
It took 55 days for a radioactivity of 1.75 x 1012 Bq to remain 0.135 Ci. What is the half-life of this radioactivity?
From the calculations, the half life of the material is 6.5 days.
What is radioactivity?The term radioactivity has to do with the spontaneous disintegration of a specie.
Uisng the formula;
N=Noe^-kt
N= amount at time t = 0.135 Ci or 4.995 ×10^9 Bq
No = amount initially present = 1.75 x 10^12 Bq
k = rate constant = ?
t = time taken = 55 days
Hence;
4.995 ×10^9 = 1.75 x 10^12e^-55k
4.995 ×10^9/1.75 x 10^12 = e^-55k
2.85 * 10^-3 = e^-55k
ln2.85 * 10^-3 = -55k
k = ln2.85 * 10^-3/-55
k = 0.1066 day-1
Half life = 0.693/ 0.1066 day-1
= 6.5 days
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law and the rate constant for the reaction.
PLEASE HELP!!!!.
A buffer solution was prepared by mixing 150.00 mL of 1.1341 mol/L of CH3COOH
and 100.00 mL of 0.831 mol/L of barium acetate. Determine the pH of the buffer
solution after the addition of 10.00 mL of 0.010 mol sulphuric acid. Kc for acetic acid
is 1.8 x 10-5
The pH of the buffer solution after the addition of sulfuric acid is determined as 4.43.
Initial moles of acid and base
The initial moles of acid and base conjugate is determined as follows;
n = CV
na₁ = (150 x 1.1341)/1000
na₁ = 0.17 mol
nb₁ = (100 x 0.831)/1000
nb₁ = 0.083 mol
Number of moles of the acid addedH₂SO4 ⇄ 2H²⁺ + SO₄²⁻
na₂ = (10 x 0.01)/1000
na₂ = 0.0001 mol
Final number of moles of the acid and basenb = 0.083 - 2(0.0001) = 0.0829 mol
na = 0.17 + 2(0.0001) = 0.1702 mol
pH of the buffer solution[tex]Ka = \frac{[CH_3COO][H^+]}{[CH_3COOH]} \\\\1.8\times 10^{-5} = \frac{0.0829(H^+)}{0.1702} \\\\H^+ = \frac{(1.8 \times 10^{-5})(0.1702)}{0.0829} \\\\H^+ = 3.696 \times 10^{-5}\\\\pH = -Log [H^+]\\\\pH = -Log (3.696 \times 10^{-5})\\\\pH = 4.43[/tex]
Thus, the pH of the buffer solution after the addition of sulfuric acid is determined as 4.43.
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Which of the following happens during an endothermic chemical change? (5 points)
Group of answer choices
Heat is released.
Net energy decreases.
Products have a higher total potential energy than the reactants.
Products have the same total potential energy as the reactants..
Answer: Products have a higher total potential energy than the reactants.
Explanation:
During endothermic reactions, energy is absorbed, meaning that the products will have more potential energy.
All of the following reactions are described as decomposition reactions except
O CuSO4.5H₂O(s) CuSO4(s) + 5H₂O(g).
O 2PbO₂ (s)
2PbO(s) + O₂(g).
O Fe(CO)(I)
Fe(s) + 5CO(g).
O H₂SO3(aq)
SO₂(g) + H₂O(l).
O NO₂(g) + H₂O(l) 4 NO(g) + 2HNO3(aq).
The reaction NO₂(g) + H₂O(l) 4 NO(g) + 2HNO3(aq) is not a Decomposition Reaction , Option E is the correct answer.
What is a Decomposition Reaction ?A reaction in which a substance break down into two or more substances is called a Decomposition Reaction.
In the given question
the reactions
CuSO4.5H₂O(s)--> CuSO4(s) + 5H₂O(g).
2PbO₂ (s) --> 2PbO(s) + O₂(g).
Fe(CO)(I)-->Fe(s) + 5CO(g).
H₂SO3(aq)-- >SO₂(g) + H₂O(l)
These are all Decomposition Reaction.
The only reaction which is not is the Reaction E
NO₂(g) + H₂O(l) 4 NO(g) + 2HNO3(aq)
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Is the chemical reaction faster when the metal is in dust form or when it's melted?
Answer:
dust form
Explanation:
because dust spreads alot faster
Draw the product you expect from the reaction of (R)-2-bromooctane with -CH3CO2- and Br-.. Use the wedge/hash bond tools to indicate stereochemistry where it exists. Include H atoms at chiral centers only. If a group is achiral, do not use wedged or hashed bonds on it.
From the mechanism shown, the major product of the reaction is (S)-(+)-2-octanol.
What is an SN2 reaction?An SN2 reaction is one in which there is an inversion of configuration and the attack of the nucleophile occurs from behind the substrate.
As shown in the mechanism attached here, the major product of this reaction is (S)-(+)-2-octanol.
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0.58 mol of Mg contains how many atoms? please show work
The number of atoms present in 0.58 mole of magnesium, Mg is 3.49×10²³ atoms
Avogadro's hypothesis1 mole of Mg = 6.02×10²³ atoms
How to determine the atoms in 0.58 mole of Mg1 mole of Mg = 6.02×10²³ atoms
Therefore,
0.58 mole of Mg = 0.58 × 6.02×10²³
0.58 mole of Mg = 3.49×10²³ atoms
Thus, 3.49×10²³ atoms are present in 0.58 mole of Mg
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describe another way in which human activities that benefit society can also cause environmental risk.
A solution of 0.20 M NaOH is used to prepare 0.10 M NaOH. How much of the 0.20 M solution is needed to prepare 455 mL of the diluted NaOH?
Taking into account the definition of dilution, 227.5 mL of the 0.20 M solution is needed to prepare 455 mL of the diluted NaOH.
What is DilutionDilution is the process of reducing the concentration of solute in solution, which is accomplished by simply adding more solvent to the solution at the same amount of solute.
In a dilution the amount of solute does not change, but as more solvent is added, the concentration of the solute decreases, as the volume (and weight) of the solution increases.
A dilution is mathematically expressed as:
Ci×Vi = Cf×Vf
where
Ci: initial concentrationVi: initial volumeCf: final concentrationVf: final volumeInitial volumeIn this case, you know:
Ci= 0.20 MVi= ?Cf= 0.10 MVf= 455 mLReplacing in the definition of dilution:
0.20 M× Vi= 0.10 M× 455 mL
Solving:
(0.10 M× 455 mL)÷ 0.20 M= Vi
227.5 mL= Vi
In summary, 227.5 mL of the 0.20 M solution is needed to prepare 455 mL of the diluted NaOH.
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The molecular geometry of the PF3 molecule is __________, and this molecule is ________.
O tetrahedral, unipolar
O trigonal pyramidal, nonpolar
O trigonal pyramidal, polar
O trigonal planar, nonpolar
O trigonal planar, polar
Answer:
C.) trigonal pyramidal, polar
Explanation:
Around the phosphorus central atom, there are 3 fluorine atoms and 1 lone pair. This makes the shape tetrahedral, but gives it a trigonal pyramidal geometry. The lone pair on the phosphorus disrupts the balance of the molecule and pulls the electrons towards it. This makes the molecule polar.