Answer:
Mn
Explanation:
Looks like Mn ( Manganese) from the Periodic Table of elements)
there are 25 electrons......25 protons ....atomic number 25 = Mn
please helpWhat’s the pH of a solution of ammonia that has a concentration of 0.335 M? The Kb of ammonia is
1.8 × 10–5
. First complete the ICE chart.
HA H3O+ AInitial
Change
Equilibrium
iii. Calculate the pH. Please show all work.
From the calculation, the pH of the solution is 4.85.
What is the pH?
The pH is defined as the hydrogen ion concentration of the solution. We have the ICE table as;
HA + H2O ⇔ H3O^+ + A^-
I 0.335 0 0
C -x +x +x
E 0.335 - x x x
Ka = 1 * 10^-14/Kb
Ka = 1 * 10^-14/1.8 × 10^–5
Ka = 5.56 * 10^-10
Ka = [H3O^+] [A^-]/[HA]
But [H3O^+] = [A^-] = x
5.56 * 10^-10 = x^2/ 0.335 - x
5.56 * 10^-10(0.335 - x ) = x^2
1.86 * 10^-10 - 5.56 * 10^-10x = x^2
x^2 + 5.56 * 10^-10x - 1.86 * 10^-10 = 0
x=0.000014 M
Now;
pH = -log 0.000014 M
pH = 4.85
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A sample of gas is at a pressure of 2.81 atm, 664 K, and a volume of 713 L. What will
be the pressure of the gas if its volume and temperature change to 126 L, and 368 K
respectively? Please help explain
Answer:
8.81 atm
Explanation:
If we let the unknown pressure be x,
[tex] \frac{713 \times 2.81}{664} = \frac{126x}{368} \\ \\ x = 8.81[/tex]
PLEASE HELP!!!
What is the correct net ionic reaction for Pb(NO3)2(aq) +2NaI(aq) → PbI2(s) + 2NaNO3(aq)?
The net ionic equation of the reaction is:
Pb²⁺ (aq) +2 I⁻ (aq) → PbI2(s)What are net ionic equations?Net ionic equations are equations where ions which remain in solution known as spectator ions are not shown in the equation. Only ions involved in formation of product are shown.
In the given equation, sodium and nitrate ions are spectator ions.
The net ionic equation of the given reaction is as follows:
Pb²⁺ (aq) +2 I⁻ (aq) → PbI2(s)In conclusion, spectator ions are not shown in net ionic equation.
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Which of these safety features aims to keep nuclear radiation contained
The safety feature aimed at keeping nuclear radiation contained is steel-reinforced concrete.
What is nuclear power plant?A nuclear power plant is a building with reactors that contain controlled nuclear reactions to produce energy.
Nuclear power plants are able to generate warm water by using atomic properties of matter (i.e.,m the process of nuclear fission), which is in turn converted into steam to move turbines.
The walls of nuclear power reactors are composed of steel-reinforced concrete in order to avoid radiation release.
In conclusion, the safety standard property that maintains nuclear radiation contained is steel-reinforced concrete.
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A student analyzed a sample of sea water and found that it contained 2.3g of NaCi, 0.005g of MgSo4, 0.234g of CaCI2 and 60.12g of H2O. Total mass of the sample is
[tex]2.3+0.005+0.234+60.12=\boxed{62.659 \text{ g}}[/tex]
Tin is used to coat tin cans for food storage. If the tin is scratched and the iron of the can exposed, will the iron corrode more rapidly or less rapidly? Explain
The scratched tin can with the iron will more rapidly corrode the iron than the tin.
What is corrosion?The corrosion can be given as the process of the oxidation of the metal into the more stable metal oxide. The chemical oxidation of the metal is attained with the surrounding available oxygen or the water vapors.
The reactivity of the Iron for the oxidation is more as compared to the tin from the reactivity series. Therefore if both tin and iron are exposed to corrosion, iron will be more rapidly corroded.
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An intravenous saline solution contains 166 mEq/L each of Na+ and Cl−.
How many moles of Na+ are in 1.30 L of the saline solution?
The moles of Na⁺ in 1.30 L is 0.2158 moles of Na⁺.
What is concentration of a solution?Concentration of a solution is the amount of solute present in a given volume of solution or solvent.
The concentration of the Na⁺ in the intravenous saline solution contains 166 mEq/L.
1 mEq/Liter = 1 mmol/L
Moles of Na⁺ in 1.30 L = M
[tex]M = {166 mEq/L} * \frac{1 mmol/L}{1 mEq/L} * \frac{1.30 L}{1000 mL} = 0.2158\:moles[/tex]
Moles of Na⁺ in 1.30 L = 0.2158 moles of Na⁺.
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Determine the empirical formulas for compounds with the following percent compositions:
. 81.68% carbon and 18.32% hydrogen
The empirical formula of a compound that has the following percent composition; 81.68% carbon and 18.32% hydrogen is C2H5.
How to calculate empirical formula?The empirical formula is a notation indicating the ratios of the various elements present in a compound, without regard to the actual numbers.
The empirical formula of a compound that has 81.68% carbon and 18.32% hydrogen can be calculated as follows:
81.68% C = 81.68g 18.32% H = 18.32gFirst, we convert mass to moles;
C = 81.68g ÷ 12g/mol = 6.81mol H = 18.32 ÷ 1g/mol = 18.3molNext, we divide each mole value by the smallest (6.81mol)
C = 6.81 ÷ 6.81 = 1H = 18.32 ÷ 6.81 = 2.7We multiply each ratio by 5 to make an whole number:
C = 1 × 2 = 2H = 2.7 × 2 = 5.4 = 5Therefore, the empirical formula of a compound that has the following percent composition; 81.68% carbon and 18.32% hydrogen is C2H5.
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Draw and name the isomers of c4h9NH2
Answer:
yhnjulllljjghbbjygbnk
Which statements about this area are true based on what you know about petrified fossils? Check all that apply.
The area was once a forest.
The area was uplifted.
The area was void of organic material.
The area was probably covered by water.
The area was covered by volcanic material.
On the basis of the area and petrified fossils, the following statements are true:
The area was once a forest.The area was probably covered by water.Thus, the correct options are A and D.
What are Petrified fossils?Petrified fossils may be defined as those which completely replace the organic form of fossils with mineral forms like stone.
The area was once a forest indicating that there must be a lot of death of organisms that are buried deep into the soil for millions of years.
This area also consists of a huge amount of water for the delocalization of dead organic matter to flow throughout the given area where the organic form is converted into mineral form.
Therefore, the correct options for this question are A and D.
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Endler's Guppies Experiment on Natural Selection
1. Identify the following elements of hypothesis-based science in this example: (a) question, (b) hypothesis, (c) prediction, (d) control group, and (e) experimental group. 2. (a) Explain how the types of data the researchers chose to collect enabled them to test their prediction. (b) What additional questions might you ask to determine the strength of these conclusions?
In conclusion, an experiment about Natural Selection includes mechanisms, explanation, estimation of the frequency of the trait and comparisons.
What is the scientific method?The scientific method is a series of step used to validate evidence and thus formulate theories.
Darwin used the scientific method to draw conclusions about the main mechanism of evolution, i.e., natural selection.
The scientific method involves making a question, providing an explanation of the hypothesis, making observations/experiments (which include experimental and control groups), and drawing conclusions.
The empirical data serve to test a hypothesis (either confirm or reject it) by contrasting its results with predictive outcomes.
The strength of the conclusions can be enhanced by using supporting evidence from other research fields (in this case, for example, the fossil record).
In conclusion, an experiment on Natural Selection includes mechanisms (question), explanation (hypothesis), estimation of the frequency of the trait in the population (prediction) and comparisons (control group).
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How would you solve
14x3-2x5=?
because if you take 42-10 = 32
32 is the answer to this question 14x3-2x5.
What is BODMAS?According to the BODMAS rule, if an expression contains brackets ((), {}, []) we have first to solve or simplify the bracket followed by 'order' (that means powers and roots, etc.), then division, multiplication, addition and subtraction from left to right.
14x3-2x5
42 -10
32
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I need to answer this one quick
Answer:
Electrochemical
Combustion
Photosynthesis
Respiration
Explanation:
The half-life of the radioactive isotope magnesium-20 is 0.600 seconds.
How long will it take for the mass of a sample of magnesium-20 to decay from 65.6 micrograms to 8.20 micrograms?
____________seconds
It will take less 1.8 seconds for the mass of a sample of magnesium-20 to decay from 65.6 micrograms to 8.20 micrograms.
What is Half-Life of radioactive a radioactive substance?The half-life of a radioactive element is the time for half the amount of a sample of the substance to decay.
After 0.6 seconds 31.25 remains
After 1.2 seconds, 15.625 remains
After 1.8 seconds, 7.9 micrograms remains.
In conclusion, it will take less 1.8 seconds for the sample to decay to 8.20 micrograms.
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The time taken for the radioactive sample to decay is 1.8 s.
What is the half life?The half life is the time taken for only half of the number of the radioactive isotopes to remain. Now we have;
No = 65.6 micrograms
N = 8.20 micrograms
t1/2 = 0.600 seconds
t = ?
Hence;
N/No = (1/2)^t/t1/2
8.20/ 65.6 = (1/2)^t/0.600
0.125 = (1/2)^t/0.600
1/8 = (1/2)^t/0.600
(1/2)^3 = (1/2)^t/0.600
3 = t/0.600
t = 3 * 0.600
t = 1.8 s
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Which example involves phase change in which heat energy is released by the substance?
Answer:
Example that involves phase change in which heat energy is released by substance:
Explanation:
If heat is removed from a substance, such as in freezing and condensation, then the process is exothermic. In this instance, heat is decreasing the speed of the molecules causing them move slower (examples: liquid to solid; gas to liquid). These changes release heat to the surroundings.3 days ago
Solid → Liquid: Melting or fusion
Gas → Liquid: Condensation
Liquid → Gas: Vaporization
Liquid → Solid: Freezing
Calculate the molarity of 29.9 g of MgS in 911 mL of solution??
0.58 is the molarity of 29.9 g of MgS in 911 mL of solution.
Define the molarity of a solution.
Molarity (M) is the amount of a substance in a certain volume of solution. Molarity is defined as the moles of a solute per litres of a solution. Molarity is also known as the molar concentration of a solution.
Given data:
Volume of solution = 911 mL=0.911L
Given the mass of MgS = 29.9 g
Molar mass of MgS = 56.38 g/mol
Moles of MgS = 0.5303299042
[tex]Molality = \frac{Moles \;solute}{Volume \;of \;solution \;in \;litre}[/tex]
[tex]Molality = \frac{0.5303299042}{0.911L}[/tex]
Molality = 0.5821403998=0.58
Hence, 0.58 is the molarity of 29.9 g of MgS in 911 mL of solution.
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QUESTION 2 1 POINT
A sample of a gas has a pressure of 248 mm Hg when the volume is 1.05 L. What is the pressure of the gas when the
volume is 3.98 L?
Answer:
65.4 mmHg
Explanation:
Using Boyle's Law,
(248)(1.05)=(pressure)(3.98)
pressure = 65.4 mmHg
Which of the following best describes the function of a plant's flowers?
A.
The flowers of a plant transport nutrients from the roots of a plant to the stems.
B.
The flowers of a plant make food for the rest of the plant.
C.
The flowers of a plant attract animals that are important for pollination.
D.
The flowers of a plant absorb water and nutrients from the soil.
The specific heat of a certain type of cooking oil is 1.75 cal/(g ·°C). How much heat energy is needed to raise the temperature of 2.50 kg of this oil from 23 ∘C to 191 ∘C?
637,980 Joules is needed to raise the temperature of 2.50 kg of this oil from 23 ∘C to 191 ∘C.
What is specific heat?The heat in calories required to raise the temperature of one gram of a substance one degree Celsius.
Q = cmΔT
where
Q = heat energy needed for that material to get desired temperature change (in Joules)
M = mass (in grams) so you have to convert from kilograms.
c = specific heat constant for the material being heated
ΔT = change in temperature
Q = (1.75)(2.17 x 1000)(191 - 23)
Q = (1.75)(2170)(168)
Q = 637,980 Joules
Hence, 637,980 Joules is needed to raise the temperature of 2.50 kg of this oil from 23 ∘C to 191 ∘C.
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13. A compound with a molar mass of 78.0 g/mol is found to contain 92.29%
carbon and 7.71% hydrogen, by mass. The molecular formula of the compound is
a. CH
b. C₂H3
c. C3H3
d. C5H₁
e. C6H6
The molecular formula of the compound is C6H6
Molecular formulaFirst, convert the percentages to moles
C = 92.9/12 = 7.74
H = 7.71/1 = 7.71
Thus, the empirical formula will be CH
[empirical formula]n = molecular formula
Empirical formula mass = 12 + 1 = 13
n = empirical formula mass/molar mass = 78/13 6
Thus, the molecular formula will be C6H6
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For the decomposition of nitrosyl bromide at 10 °C
2 NOBr(g)2 NO(g) + Br2(g)
the average rate of disappearance of NOBr over the time period from t = 0 s to t = 25.7 s is found to be 7.36×10-4 M s-1.
What is the average rate of appearance of Br2 over the same time period?
M s-1.
From the calculation, the rate of appearance of Br2 is 1.472 * 10^-3 M s-1
What is the rate of reaction?The rate of reaction refers to how fast or slow that reactants disappear or the products are formed .
Now;
We know that;
-d[NOBr]/dt = 1/2 d[Br2]/dt
Hence;
d[Br2]/dt = 2[-d[NOBr]/dt ]
d[Br2]/dt = 2 (7.36×10-4 M s-1)
d[Br2]/dt = 1.472 * 10^-3 M s-1
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What are the noble gases
Answer:
Noble gases are rare elements (gases) with extreme stability and a very low reactivity rate.
Some examples are neon, argon, helium etc.
Hope it helps!!
Answer:
Helium, neon, argon, krypton, xenon, and radon.
Explanation:
The chemical elements in group 18 of the periodic chart are the noble gases. They have the most valence electrons that their outer shell can support, making them the most stable. As a result of their inherent stability, they rarely interact with other components.
Other characteristics of the noble gases are that they all conduct electricity, fluoresce, are odorless and colorless, and are used in many conditions when a stable element is needed to maintain a safe and constant environment. These are the 6 noble gases:
HeliumNeonArgonKryptonXenonRadonAlthough the phrase "inert gases" was once used to describe the noble gases, it is not entirely true given that some of them do participate in chemical processes.
Chemical properties:
Under normal circumstances, the noble gases are nonflammable, tasteless, colorless, and odorless. Because it was earlier thought that they had a valence of zero, or that their atoms couldn't mix with those of other elements to create compounds, they were originally given the group 0 designation in the periodic table. However, it was eventually determined that some do in fact combine to create compounds, which led to the label's demise. Full valence electron shells are present in noble gases. The only electrons that often take part in chemical bonding are valence electrons, which are an atom's outermost electrons. Due to their great stability, complete valence electron shell atoms have little to no inclination to gain or lose electrons and do not frequently establish chemical bonds. But unlike lesser noble gases like helium, larger noble gases like radon are bound together by electromagnetic force less tightly, making it simpler to remove outside electrons from hefty noble gases. The noble gases can be combined with the electron configuration notation to create the noble gas notation as a consequence of a complete shell.
To do this, the electron configuration is written starting with the nearest noble gas that comes before the element in issue, and then it is carried from there. For instance, the noble gas notation is [Ne] 3s2 3p3, whereas the electron notation for phosphorus is 1s2 2s2 2p6 3s2 3p3. In addition to being shorter than writing down the whole notation of atomic orbitals, this more condensed notation makes it simpler to identify elements.
Of all the noble gas compounds that have been created, xenon compounds are the most prevalent. [33] Most of them consist of a xenon atom in the +2, +4, +6, or +8 oxidation state coupled to an extremely electronegative element, such fluorine or oxygen, as in xenon difluoride (XeF).
2), xenon tetrafluoride (XeF
4), xenon hexafluoride (XeF
6), xenon tetroxide (XeO
4), and sodium perxenate (Na
4XeO
6). Xenon reacts with fluorine to form numerous xenon fluorides according to the following equations:
Xe + F2 → XeF2
Xe + 2F2 → XeF4
Xe + 3F2 → XeF6
Some of these compounds have found use in chemical synthesis as oxidizing agents; XeF
2, in particular, is commercially available and can be used as a fluorinating agent.
In the above reaction, how many moles of nitrogen gas can theoretically be produced by 2.177 moles of N2H4, assuming there is an excess of N2O4?
The number of moles of nitrogen that can be produced theoretically will be 3.2655 moles.
Stoichiometric problemThe equation of the reaction is as follows:
[tex]2N_2H_4 + N_2O_4 --- > 3N_2 + 4H_2O[/tex]
The mole ratio of [tex]N_2H_4[/tex] reacted to that of [tex]N_2[/tex] produced is 2:3.
Thus, with 2.177 moles of [tex]N_2H_4[/tex] , the theoretical number of moles of [tex]N_2[/tex] can be calaculated as:
3/2 x 2.177 = 3.2655 moles
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Can someone please help me out? Its due by midnight tonight!!!!
Calculate the pH for the following weak acid.
A solution of HCOOH has 0.19M HCOOH at equilibrium. The Ka for HCOOH is 1.8×10−4 . What is the pH of this solution at equilibrium?
The pH of the solution is obtained as 2.23.
What is the pKa?The pKa shows the extent to which an acid is dissociated in solution. Now we have;
HCOOH(aq) + H2O(l) ⇔ HCOO-(aq) + H30+(aq)
Ka = [HCOO-] [ H30+]/[ HCOOH]
But = [HCOO-] = [ H30+] = x
Ka = x^2/[HCOOH]
x = √Ka [HCOOH]
x = √0.19 * 1.8×10−4
x = 5.8 * 10^-3
pH = - log (5.8 * 10^-3)
pH = 2.23
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Part G
The compound Iron oxide can exist with either iron(II) ions or Iron(III) ions. Conduct Internet research to learn about the
differences between iron(II) oxide and iron(III) oxide. Give the chemical formula for each compound. Describe their
appearance and uses. Based on your findings, are these two forms of the same compound, or are they two completely
different compounds?
BIU xX² X₂
parameters
chemical formula
appearance
uses
10pt
V
iron(II)oxide
AvZv = = = = = = V V
Iron(III) oxide
Answer:
Therefore the theoretical density of iron is 7.877 g/cm³ .
Therefore the number of vacancy per cm³ is
Explanation:
What are distinguishing features of animals? A) Generally an animal body exhibits a definite symmetry, form and shape. B) Growth of the body occurs proportionately. C) Reserved food is glycogen. D) All of the above.
Answer:
A
Explanation:
Answer:
its D) all of the above
Explanation:
i learned this is like 6th grade
The answer to this question
1) There are only single bonds between the carbon atoms, so the ending is 'ane'. Thus, the answer is 2-methylbutane.
2) There is one triple bond between one pair of carbon atoms, so the ending is 'yne'. So, the answer is 2-butyne.
3) There is one double bond between one pair of carbon atoms, so the ending is 'ene'. So, the answer is 2-butene.
Consider the following reaction:
2KI (aq) + Pb(NO3)2(aq) -> 2 KNO3(aq) + Pbl2(s)
What minimum volume of 0.200 M Kl(aq) is required to completely react with 155.0 mL of a 0.112 M Pb(NO3)2 solution?
A. 174 mL
B. 43.4 mL
C. 86.8 mL
D. 348 mL
Answer:
B. 43.40 mL
Explanation:
We are required to determine the volume of 0.200 M Kl(aq).
We have; 155.0 mL of a 0.112 M Pb(NO3)2 solution.
We know that molarity of a solution is contained in 1 L or 1000 mL or 1000 cm³.
Hence,
0.112 M Pb(NO3)2 is contained in 1000 mLx mol Pb(NO3)2 is contained in 155.0 mL[tex]x \: mol \: = \frac{155 \times 0.112}{1000} \\ = 0.01736 \: moles[/tex]
= 0.01736 moles of Pb(NO3)2
We have a mole ratio of 2: 1 (KI : Pb(NO3)2).
To obtain the number of moles of KI; we divide by half the moles of Pb(NO3)2 (aq);
(0.01736)/2
= 0.00868 moles KI
0.20 moles KI is contained in 1000 mL
0.00868 moles KI is contained in x mL
[tex]x \: ml \: = \frac{0.00868 \times 1000}{0.20} [/tex]
= 43.40 mL
Therefore the volume of KI required to react completely with 0.112 M Pb(NO3)2 is 43.40 mL
You drink part of your bottle of water, leaving 160 g in the bottle. When you purchased the water, it had a temperature of 10oC. After carrying the bottle around for awhile, you take a sip and find that the water is an unpleasantly warm 35oC. How much heat energy did the water left in the bottle absorb? Water has a specific heat capacity of 4.2 J/(g * oC).
The energy that the water in the bottle absorbed is obtained as 16800 J.
What is the specific heat capacity?The specific heat capacity of the water refers to the energy that is required to raise the temperature of 1Kg of the water by 1 degree.
Now we have the following;
mass (m) = 160 g
temperature change dT = ( 35oC - 10oC)
specific heat capacity (c)= 4.2 J/(g * oC).
Now;
H = mcdT
H = 160 g * 4.2 J/(g * oC) * ( 35oC - 10oC)
H = 16800 J
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Hierarchies and schemes are important for?
Answer:
Hierarchies and schemes are important for organizing information. They provide a way to group related information together and to see the relationships between different pieces of information.