Answer: 2.5 grams
Explanation:
Expression for rate law for first order kinetics is given by:
[tex]t=\frac{2.303}{k}\log\frac{a}{a-x}[/tex]
where,
k = rate constant
t = age of sample
a = let initial amount of the reactant
a - x = amount left after decay process
a) to calculate the rate constant:
Half life is the amount of time taken by a radioactive material to decay to half of its original value.
[tex]t_{\frac{1}{2}}=\frac{0.693}{k}[/tex]
[tex]k=\frac{0.693}{2years}=0.346years^{-1}[/tex]
b) to find amount left after 4 years
[tex]4=\frac{2.303}{0.346}\log\frac{10}{a-x}[/tex]
[tex](a-x)=2.5g[/tex]
Thus 2.5 g of cesium would remain from a 10 g sample after 4 years
a solution of hydrochloric acid contains 1.5 moles of the solute in 2.0 liters of solution. calculate the molarity of this solution
Answer:
0.75 M
Explanation:
Molarity = moles of solute / liters of solution
so;
Molarity = [tex]\frac{1.5 Moles}{2.0 Liters}[/tex]
According to molar concentration, the molarity of this solution is 0.75 molar.
What is molar concentration?Molar concentration is defined as a measure by which concentration of chemical substances present in a solution are determined. It is defined in particular reference to solute concentration in a solution . Most commonly used unit for molar concentration is moles/liter.
The molar concentration depends on change in volume of the solution which is mainly due to thermal expansion. Molar concentration is calculated by the formula, molar concentration=mass/ molar mass ×1/volume of solution in liters.
In terms of moles, it's formula is given as molar concentration= number of moles /volume of solution in liters.Substitution in formula gives, molarity= 1.5/2=0.75 M
Thus, the molarity of this solution is 0.75 molar.
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1
Net ionic equations remove spectator ions and shows only the chemical species that are involved in the chemical reaction. Write the net ionic equation for the following acid base reaction.
Molecular Equation: 2 HCl (aq) + Mg(OH)2 (aq) → MgCl2 (aq) + 2 H2O (l)
Complete Ionic: 2 H+ (aq) + 2 Cl– (aq) + Mg2+ (aq) + 2 OH– (aq) → Mg2+ (aq) + 2 Cl– (aq) + 2 H2O (l)
Net Ionic Equation: ______________________________________________________
Answer:
The reaction of an acid and a base is called a neutralization reaction. ... However, in the reaction between HCl(aq) and Mg(OH) 2(aq), additional molecules of HCl and ... First, we will write the chemical equation with the formulas of the reactants ... The chloride ions are the only spectator ions I THINKS
Explanation:
How does the mass and height of an object affect the gravitational potential energy?
Answer: The higher up an object an is the greater it’s gravitational potential energy. This is because a tree has more mass, so it needs to be given more gravitational potential energy to reach the same height. So a change in gravitational potential energy also depends on the mass of the object that is changing height
Explanation:
The gravitational potential energy (P.E) depends on the mass of the body and the height at which it travels, the two quantities will therefore dictate the work done on the object which is eventually the same as magnitude of the gravitational potential energy P.E.
It is assumed that gravitational pull acts toward the earth surface. The more the object move upward the more the work is done on the object to pull it down.
This work done is equal to the gravitational potential energy P.E which can be expressed as:
P.E = mgh
Where
m = mass of the body
g = gravitational field strength
h = height
We can have different masses of object at different heights, but gravitational field strength will always remain constant on earth.
Since the gravitational potential energy P.E depend on the mass of the body and the height at which it travels, the two quantities will therefore dictate the work done on the object which is eventually the same as magnitude of the gravitational potential energy P.E.
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The diagram shows Niels Bohr’s model of an atom.
A small green circle labeled Proton is surrounded by 4 concentric circles. The space inside the first concentric circle is labeled N = 1; the space between the first and second circle is labeled N + = 2; between the second and third N = 3, and between the third and fourth N = 4. Oblong gray shapes labeled Electron appear on the second and third concentric circles.
What happens when the electron moves from the first energy level to the second energy level?
Energy is absorbed, and an emission line is produced.
Energy is released, and an emission line is produced.
Energy is absorbed by the atom.
Energy is lost from the atom.
Answer:
Energy is absorbed by the atom.
Explanation:
Pls help me with this will mark brainliest
Answer:
Pulmonary circulation moves blood between the heart and the lungs. The oxygenated blood then flows back to the heart. Systemic circulation moves blood between the heart and the rest of the body. It sends oxygenated blood out to cells and returns deoxygenated blood to the heart
Explanation:
Why are prefixes not used in naming ionic compounds?
A. Two ions can combine in only one combination.
B. The number of ions is not fixed in a compound.
C. A roman numeral is used instead of a prefix
D. A subscript follows each name instead of a prefix.
Answer:
A.
Explanation: thats what i got right on the quiz lol
Prefixes are not used in naming ionic compounds because two ions can combine in only one combination.
It is common in organic chemistry and with a few other molecular species, to name the compound using a prefix such as di, tri, tetra etc to indicate the positions of moieties in the molecule. This is important because there could be several possible combinations of atoms in a molecule.
In the case of ionic compounds, the combining ions can only have one possible arrangement.
Hence, the reason why prefixes are not used in naming ionic compounds is because two ions can combine in only one combination.
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Photosynthesis produces (4 points)
carbon dioxide and energy
carbon dioxide and oxygen
glucose and oxygen
glucose and carbon dioxide
(I'm pretty positive it's C, but correct me if I'm wrong)
Answer:
Glucose and oxygen is produced during photosyntheis
Explanation:
Carbon dioxide and water are required for photosyntheis producing oxygen and glucose
Answer:
C.Glucose and oxygen
this is a multiple choice question. one of the answer from the option given is correct.Could you please help!!My sister needs help but she doesn't trust me '_' why am i even saying this, no one asked
6.What are the main
sources of water pollution?
a) Plastic, paper, metal
b) Snail in water
c) Agriculture, industry and community
C.
i cant explain why..................
What can happen when tectonic plates move a few centimeters?
Answer:
whole continents can move.
You have nitrogen gas (N2) at a pressure of 0.5 atm, a volume of 25000 mL, and a temperature of 300 K, how many grams of nitrogen are present?
Answer:
About 7.109g
Explanation:
25000mL is the same as 25 liters.
[tex]PV=nRT \\\\0.5 (25)=n (0.0821) (300) \\\\n\approx 0.508[/tex]
Multiplying this by the molar mass of nitrogen, you get about 7.109 grams of nitrogen. Hope this helps!
What is the name of Al2(CO3)3 ?
Answer: Aluminum Carbonate
Explanation:
Answer:
Aluminum carbonate.
Explanation:
It is an aluminum salt form of carbonic acid.
Which substances are products of a fermentation reaction?
1.water and carbon dioxide
2.alcohol and carbon dioxide
3.soap and glycerol
4.ester and water
Answer:
2.alcohol and carbon dioxide
Explanation:
Fermentation is a metabolic process which is used to produce chemical changes in various organic substances. This process is used in many fields including biochemistry, where it is defined as the "extraction of energy from carbohydrates in the absence of oxygen". The main substances produced from fermentation reaction are alcohol, carbon dioxide and lactic acid.
Name the following 3 structural formulas correctly, in order from left to right
Answer:
1. Methyl propanoate.
2. Propanol.
3. 2–pentyne
Explanation:
1. The functional group in this case is ester. We name ester by naming the group after the functional group (–COO) then followed by the parent compound with the name ending with –oate.
The group after the functional is methyl i.e —CH3.
The parent compound has 3 carbon i.e propane. The functional group replaces the –e in propane with –oate.
Therefore, the name of the compound is:
Methyl propanoate.
2. In this case the functional group is
–OH i.e alcohol.
The compound has 3 carbon i.e propane. The functional group replaces the –e in propane with –ol.
Therefore, the name of the compound is:
Propanol.
3. The triple bond represents the functional group in this case i.e alkyne. We'll give the triple bond the lowest low count by counting from the left. The triple bond is at carbon 2.
The compound has 5 carbon i.e pentyne since it contains triple.
The name of the compound is:
2–pentyne
Give two examples of solutions that you might find or prepare in a kitchen.
Explanation:
solid liquid
solid gas
liquid solid
which accurately describes development?
Answer:
changing while growing
Explanation:
Answer: the answer is a
When KCl dissolves in water
Answer:
They form K₂O (Potassium oxide) and HCl (Hydrochloric acid). This is because K and H are positively charged and O and Cl are negatively charged and cations only bond with anions.
Consider the intermediate equations: 3 equations.
C(s) + O2(g) --> CO2(g) Delta H1 = -393.5 kJ
2CO(g) + O2(g) --> 2CO2(g) Delta H2 = -566.0 kJ
2H2O(g) --> 2H2(g) + O2(g) Delta H3 = 483.6 kJ
With the overall reaction:
C(s) + H2O(g) --> CO(g) + H2(g) Delta Hrxn = ?
QUESTION 1:
What must be done to calculate the enthalpy of reaction?
The first must be halved.
The first must be reversed.
The second must be halved.
The second must be reversed.
The third must be halved.
The third must be reversed.
QUESTION 2:
What is the overall enthalpy of reaction?
Delta Hrxn = ____ kJ
Answer:
C. The second equation must be halved
D. The second equation must be reversed
E. The third equation must be halved.
Delta Hrxn= 131.3 kJ
Explanation:
The correct answer is -582 KJ.
What is the enthalpy of reaction?
Enthalpy is the heat content of a system.The enthalpy change of a reaction is roughly equivalent to the amount of energy lost or gained during the reaction.A reaction is favored if the enthalpy of the system decreases over the reaction.What is the overall enthalpy of the reaction?
Equal to the sum of the standard enthalpies of the intermediate reaction steps is called overall enthalpyLearn more about enthalpy below,
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ANSWER IT CORRECTLY PLEASE!!
The Osmotic pressure of blood is 7.65 ATM at 310 k. An aqueous solution of glucose is isotonic with blood has the percentage by volume
a.5.41%
b.3.54%
c.4.53%
d.53.4%
Answer:
Explanation:
Pv = n RT
P =7.65, T= 310K, for glucose n = moles= weight/molar mass= weight/180, R is gas constant
7.65* V =W/180 *0.0821 * 310
w/v= 7.65*180/0.0821*310 = 1377/25.45 = 54.10 =5.4%
What happens to the total mass of a substance undergoing a physical change
Answer: It stays the same
Explanation:
Answer: it stays the same (A)
Explanation:
did the test online got 100%
A 10.0 g sample of an unknown liquid is vaporized at 120.0°C and 5.0 atm. The volume of the vapour is found to be 568.0 mL. The liquid is determined to be made up of 84.2% carbon and 15.8% hydrogen. What is the molecular formula for the liquid?
Answer:
C8H16
Explanation:
First thing to do here is to calculate the molar mass of the compound
Mathematically;
molar mass = mass/number of moles
we can calculate the number of moles using the ideal gas equation
Mathematically;
PV = nRT
n = PV/RT
where p is the pressure at 5 atm
V is the volume at 568 ml = 568/1000 = 0.568 L
R is the molar gas constant which is 0.0821
T is the temperature which is 120+ 273 = 393k
Inserting these values into the equation, we have
n = (5 * 0.568)/(0.0821 * 393)
n = 0.088 moles
So the molar mass = 10/0.088
= 114 g/mol
Now let’s go to the percentages
C = 84.2/12 = 7.016666666666667
H = 15.8/1 = 15.8
divide by the smallest
C = 7.016666666666667/7.016666666666667 = 1
H = 15.8/7.016666666666667 = 2 approximately
The empirical formula is CH2
So for the molecular formula, we have;
(12 + 2)n = 114
14n = 114
n = 114/14 = approximately 8
So the molecular formula of the liquid will be (CH2)n = C8H16
What is the total energy required to break all the bonds in 1 mol propanol,
C3H8O?
Answer:
The total energy to break all the bonds in 1 mole of 1-propanol, C₃H₈O, is 4411 kJ/mol
Explanation:
We note that propanol, C₃H₈O is also known as 1-propanol is written as follows;
CH₃CH₂CH₂OH which gives
CH₃-CH₂-CH₂-OH
Hence, the total number of bonds are;
C-H Bonds = 3 + 2 + 2 = 7
C-O Bonds = 1
O-H Bond = 1
C-C Bonds = 2
The bond energies are as follows;
C-H Bonds = 413 kJ/mol
C-O Bonds = 358 kJ/mol
O-H Bond = 468 kJ/mol
C-C Bonds = 347 kJ/mol
Energy required to break the bonds in 1-propanol is therefore;
C-H Bonds = 413 kJ/mol × 7 = 2,891 kJ/mol
C-O Bonds = 358 kJ/mol × 1 = 358 kJ/mol
O-H Bond = 468 kJ/mol × 1 = 468 kJ/mol
C-C Bonds = 347 kJ/mol × 2 = 694 kJ/mol
The total energy to break all the bonds in 1 mole of 1-propanol = 4411 kJ/mol.
4. Which of these terms describes the process of acid rain wearing away limestone?
Acryptic erosion
B.chemical weathering
C.cryptobiotic weathering
D.chemical erosion
Answer:
B. Chemical weathering
Explanation:
Erosion is the process whereby the soil and rocks are washed away by wind, water, ice or gravity.
Weathering is the process of weakening and breaking down of rocks and minerals either by non-living (abiotic) or living (biotic) factors or by both, such as temperature changes, plants and animals, acids, salts and water, etc.
From the above definitions, it can be seen that acid wearing away limestone is a rock weathering process by a non-living agent, an acid.
Option A is wrong because the process is weathering
Option B is correct because an acid is a chemical and the process involved is weathering
Option C is wrong because an acid is non-living
Option D is wrong because the process involved is weathering
PLSSS HELPPP MEEE WITH THIS QUESTIONNNNN NO GUESSING PLSSSS
Which process is shown in the plant cell below?
A= cell growth
B= cell reproduction
C= metamorphosis
D= photosynthesis
Answer:
B
Explanation:
Well, the cells are going through mitosis, which means that when the divide, they are going to be identical sister cells. Anyways, they are
Tyler measured the force of his grip. Which is the most likely reading?
A.
190kg
B.
190N
C.
1 lb
D.
20,000 N
E.
5 seconds
F.
18mg
Answer:
190n
Explanation:
190 190 and because it is easy to understand if you didn't understand my answer ask any man
Why does diamond not conduct electricity
Answer: no free electrons
Explanation: Diamond is very hard due to the strong covalent bonds and rigid tetrahedral 3d arrangement. It does not conduct electricity, as there are no electrons free to move and carry charge through the structure.
Does the conductivity increase or decrease?
O It increases at first, then decreases.
O It continuously decreases
O It continuously increases
O lt decreases at first, then increases
Answer:
It continuously decreases.
Explanation:
the thermal motion makes the electrons to collide and disturb the free flow. Thus, conductivity is decreased.
What does the pH of a solution measure?
O A. Color
O B. Volume
O c. Temperature
O D. Acidity
Answer:
D is the correct answer acidity
Explanation:
pH is the logarithmic measurement of the H3O+-concentration in water solutions.
By definition: pH = -log[H3O+]
Example: [H3O+] = 1.0*10-7 mol/L in neutral, pure water (at 25oC), so
pH = -log(H3O+) = -log(1.0*10-7) = 7.0
Which group in the periodic table contains the three elements with the highest
electrical conductivities?
OA) Group 8
B) Group 12
C) Group 11
D) Group 7
Answer:
Group 12
Explanation:
Group 12 is also called a transition metal group. This group in the periodic table lies in between the groups or tables. These metals are classified as the transition metal in the table.
These metals are found from the group number 3 to 12. In the periodic table, These transition elements are ductile and malleable. These metal conduct heat and electricity.
These elements are generally called dense and less to react to the alkaline metal. Iron, copper-silver, gold is the most important transition metal.
Answer:
Group 11
Explanation:
Pf
What is a chemical solution and what are the names of its components?
Answer:
A chemical solution is defined as a homogeneous mixture of two or more substances. There are two components of chemical solution that include solute and solvent.
Solute is the component that get dissolved in another substance and solvent is the substance that dissolve solute.
For example: carbon dioxide in water. Where carbon-dioxide is solute and water is solvent.
How will you test for the gas which is liberated when hcl reacts with an active metal ?
