Answer:
Mass of a given chemical element or compound divided by the amount of substance.
(g/mol)
How much cesium (half-life = 2 years) would remain from a 10 g sample after
4 years?
O A. Og
OB. 8g
O c. 59
O D. 29
SUBMIT
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
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:
How will you test for the gas which is liberated when hcl reacts with an active metal ?
Elements that form ionic bonds generally have how many valence electrons?
Answer:
they should have a number that can completely transfer and fill the other atom
Explanation:
example:
sodium(2.8.1)and Chlorine(2.8.7)the sodium will give chlorine the 1 valence electrobo so they both become stable(2.8)±and(2.8.8)–
magnesium(2.8.2)and oxygen(2.6)same way as above to abtain mg(2.8)±²and oxygen(2.8)–²
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.
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
What can happen when tectonic plates move a few centimeters?
Answer:
whole continents can move.
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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At STP how many moles of
argon gas are present in 6.5
liters of argon gas
Answer:
0.289 molIn order to determine the number of moles of the given volume of Ar, divide the given volume by the molar volume of an ideal gas,
22.710 L/mol
Explanation:
So you have a volume of 6 .5
6.5L / 22.710 L/mol
L is eliminate .
6.5/ 22.710 L/mol = 0.286 mol
Using the older STP values of 0 ∘ C or 273.15 K , and pressure of 1 atm , molar volume is 22.414 L/mol .
6.5L /22.414 L/mol .= 0.289 mol
A solution of Co(NO₃)₂ is electrolyzed using a 15.0A current for 1.00 hour and Co(s) is produced at the cathode. Calculate the moles of electrons that was used to electrolyze the solution? Calculate the moles and mass of Co(s) produced at the cathode?
Answer:
1. 0.56 mole of electron.
2. 0.28 mole of Co .
3. 16.52g of Co.
Explanation:
The following data were obtained from the question:
Current (I) = 15A
Time (t) = 1 hr = 1 x 60 x 60 = 3600secs
Next, we shall determine the quantity of electricity, Q flowing in electrolyte. This is illustrated below:
Quantity of electricity (Q) = current (I) x Time
Q = It
Q = 15 x 3600
Q = 54000C.
1. Determination of the moles of electrons used to electrolyzed the solution. This is illustrated below:
96500C = 1 mole of electron
Therefore, 54000C = 54000/96500 = 0.56 mole of electron.
Therefore, 0.56 mole of electron was used to electrolyze the solution.
2. Determination of the number of mole of Co produced at the cathode. This is illustrated below:
At the cathode:
Co2+ + 2e —> Co
From the balanced equation above,
2 moles of electron produce 1 mole of Co.
Therefore, 0.56 mole of electron will produce = 0.56/2 = 0.28 mole of Co.
Therefore, 0.28 mole of Co is produced at the cathode.
3. Determination of the mass of Co produced at the cathode. This can be achieved by doing the following:
Molar mass of Co = 59g/mol
Number of mole of Co = 0.28 mole
Mass of Co =..?
Mass = mole x molar mass
Mass of Co = 0.28 x 59
Mass of Co = 16.52g
Therefore, 16.52g of Co is produced at the cathode.
If the atmospheric pressure in the laboratory is 1.2 atm, how many moles of gas were in each syringe? (Hint: Choose one volume and temperature pair from your data table to use in your ideal gas law calculation.)
Answer:
A: 2.525 x 10-4 mol
B: 2.583 x 10-4 mol
Explanation:
Part A:
Data Given:
. Temperature of water (H2O) = 21.3°C
Convert Temperature to Kelvin
T = °C + 273
T = 21.3 + 273 = 294.3 K
volume of (H2O) gaseous state = 5.1 mL
Convert mL to liter
1000 mL = 1L
5.1 ml = 5.1/1000 = 0.0051 L
Pressure = 1.2 atm
. no. of moles = ?
Solution
no. of moles can be calculated by using ideal gas formula
PV = nRT
Rearrange the equation for no. of moles
n=PV/RT......... (1)
where
P = pressure
V = Volume
T= Temperature
n = Number of moles
R = ideal gas constant
where
R = 0.08206 L.atm/ mol. K
Now put the value in formula (1) to calculate no. of moles of
n = 1.2 atm x 0.0051 L / 0.08206 L.atm.mol-1. K-1 x 294.3 K
n = 0.0061 atm.L / 24.162 L.atm.mol-1
n = 2.525 x 10-4 mol
no. of moles of gas (H2O) = 2.525 x 10-4 mol
Part B:
Data Given:
Temperature of water (H2) = 21.3°C
Convert Temperature to Kelvin
T = "C + 273
T= 21.3 + 273 = 294.3 K
volume of (H2) gas = 5.2 mL
Convert mL to liter
1000 mL = 1 L
5.2 ml = 5.2/1000 = 0.0052 L
Pressure = 1.2 atm
. no. of moles = ?
Solution
no. of moles can be calculated by using ideal gas formula
PV = nRT
Rearrange the equation for no. of moles
n= PV / RT......... (1)
where
P = pressure
V = Volume
T= Temperature
n = Number of moles
R = ideal gas constant
where
R = 0.08206 L.atm/mol. K
Now put the value in formula (1) to calculate no. of moles of
n = 1.2 atm x 0.0052 L/0.08206 L.atm.mol-1. K-1 x 294.3 K
n = 0.0062 atm.L/ 24.162 L.atm.mol-1
n = 2.583 x 10-4 mol
I
no. of moles of gas (H2) = 2.583 x 10-4 mol
Which of the following reactions shows that the formation of CO2 releases
393.5 kJ/mol?
A. C(s) + O2(g) → CO2(g) + 393.5 kJ
O B. C(s) + 20(g) + 393.5 kJ → CO2(9)
O C. C(s) + O(g) + CO2(g) + 393.5 kJ
D. C(s) + O2(g) + 393.5 kJ → CO2(g)
Answer:
A. C(s) + O2(g) → CO2(g) + 393.5 kJ
Explanation:
The formation of carbon IV oxide (CO2) is an exothermic process. n exothermic process is a chemical process in which heat is evolved. Speaking in lay man's terminology, heat is one of the 'products' of the reaction. This implies that heat is evolved by the process.
The formation of CO2 is always a combustion reaction where heat is evolved or released by the reaction system. Hence the reaction could be shown as;
C(s) + O2(g) → CO2(g) + 393.5 kJ
This implies that 393.5 kJ of energy is released in the reaction in the form of heat. Hence the answer given in the answer box.
Answer: C(s) + O2(g) → CO2(g) + 393.5 kJ
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 asap pls !!
Answer:
basic solution.
Explanation:
has a pH of 12.
it turns clear indicator pink.
it contains hydroxide ions which conduct electricity
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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Which of these is NOT an example of how your community uses natural
resources?
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.
Please look at the photo and identify what’s in it!
Answer:
Explanation:
A battery
Answer:
Ac motor is in this images
In the lab, a student adds 4.5 g of sodium chloride (NaCl) to 100.0 g of water. Calculate the molality of the solution.
Answer:
0.77mol/Kg.
Explanation:
The following data were obtained from the question:
Mass of NaCl = 4.5g
Mass of water = 100g.
Molality =...?
Next, we shall determine the number of mole in 4.5g of NaCl. This can be obtained as follow:
Mass of NaCl = 4g.
Molar mass of NaCl = 23 + 35.5 = 58.5g/mol
Number of mole NaCl =..?
Mole = Mass /Molar Mass
Number of mole of NaCl = 4.5/58.5
Number of mole of NaCl = 0.077 mole.
Next, we shall convert 100g of water to kilograms. This is illustrated below:
1000g = 1kg
Therefore, 100g = 100/1000 = 0.1Kg.
Finally, we can determine the molality of the solution as follow:
Molality is simply defined as the mole of solute per unit kilogram of solvent (water). Mathematically, it is represented as:
Molarity = mole of solute / kg of solvent
Mole of solute, NaCl = 0.077 mole
Kg of solvent = 0.1kg
Molality = 0.077mol/0.1kg
Molality = 0.77mol/Kg
The molarity of the solution is 0.77mol/Kg.
Calculation of the molarity of the solution:
Since
Mass of NaCl = 4.5g
Mass of water = 100g.
Here,
Mass of NaCl = 4g.
Molar mass of NaCl = 23 + 35.5 = 58.5g/mol
Now
Mole = Mass /Molar Mass
= 4.5/58.5
= 0.077 mole.
Now
1000g = 1kg
So,
100g = 100/1000 = 0.1Kg.
Now
Molarity = mole of solute / kg of solvent
Mole of solute, NaCl = 0.077 mole
Kg of solvent = 0.1kg
So,
Molality = 0.077mol/0.1kg
= 0.77mol/Kg
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scientists often work on projects for a long time and fail to see sources of error in their research. Which process allows an outside expert to look at the scientist’s project and point to sources of error?
Answer:
Replication
Explanation:
In science, the work of a scientist is regarded as authentic if other experts in other places can follow the same steps as he/she claimed to follow and arrive at the same result.
For example, a scientist in California, United States of America may carry out a research and publish his findings. Another scientist in Christchurch New Zealand following exactly the same procedure is expected to arrive at the same results as the original researcher if there were no errors in the work.
However, where there are disparities in results, the scientist in Newzealand may discover errors that were unknown to the original researcher in the united States. The New Zealand scientist was carrying out a process known as 'replication'. That is, repeating a scientific research in order to obtain the same results thereby validating the research.
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
When electrons are removed from the outermost shell of a calcium atom, the atom becomes
A)an anion that has a larger radius than the atom.
B) an anion that has a smaller radius than the atom.
C)a cation that has a larger radius than the atom.
D) a cation that has a smaller radius than the atom.
Answer:
A cation that has a smaller radius than the atom.
Explanation: when electrons are removed from the outermost shell of a calcium atom, the atom becomes a cation that has a smaller radius than the atom.
When electrons are removed from the outermost shell of a calcium atom, the atom becomes a cation that has a smaller radius than the atom. Therefore, the correct option is option D.
What is atom?Atom, the smallest unit of matter that may be separated without releasing electrically charged particles. It is also the smallest unit of matter with the characteristics of a chemical element. As a result, the atom is indeed the fundamental building component of chemistry.
The majority of the atom comprises empty space. The rest of the structure is made up of a positive-charged nucleus of neutrons and protons surrounding by a cloud of electrons with negative charges. In comparison to electrons, the lightest energized particles in nature, the nuclei is small and dense. When electrons are removed from the outermost shell of a calcium atom, the atom becomes a cation that has a smaller radius than the atom.
Therefore, the correct option is option D.
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How much heat is added if 0.2067g of water is increased in temperature by 0.855
degrees C?
Answer:
0.756 J
Explanation:
Temperature change (delta T) = 0.855 degrees Celsius
Mass of water (m) = 0.2067 g
Specific heat capacity of water (c) = 4.28 J/g degrees C
Heat added = m * c * delta T
= (0.2067 * 4.28 * 0.855) J
= 0.756 J
The pressure exerted by 0.002 moles of a gas in a 500 mL container at 25oC is:
Answer:
0.1715 atm
Explanation:
We use the Ideal gas equation to calculate this
Mathematically;
PV = nRT
rearranging, we have
P = nRT/V
from the question, we have
n = 0.002 moles
R = 0.082
T = 250 = 250 + 273 = 523 K
V = 500 ml = 500/1000 = 0.5 L
Plugging the values we have;
P = (0.002 * 0.082 * 523)/0.5
P = 0.1715 atm
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%
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
The temperature of a piece of copper with a mass of 95.4g increases from 25 degrees Celsius to 48.0 degrees Celsius when the metal absorbs 849 J of heat. What is the specific heat capacity of copper?
Answer:
The answer is 3.87 J/g°C
Explanation:
Here is the equation we are going to use:
[tex]C=\frac{q}{mT}[/tex]
C= specfic heat in J/g°C
q = heat in joules (J)
m = mass in grams (g)
T = change in temperature
Here is what is given:
q = 849 J
m = 95.4 g
T = 48.0 - 25.0 = 23°C
Find:
Specific heat capacity in J/g
The first thing we are going to do is plug everything into the equation:
[tex]C = \frac{849J}{(9.54g)(23degreesC)}[/tex]
Then we are going to solve for C
[tex]C = \frac{849J}{219.42gC} = 3.87 J/gCelsius[/tex]
Hope this helps!
Answer:
The answer is 3.87 J/gC
C2H5OH(l)+CH3COOH(l) → CH3COOC2H5(l)+H2O(l) If the yield of ethyl ethanoate obtained when 20.00 g of ethanol is reacted with excess ethanoic acid is 30.27 g, calculate the percentage yield
Answer:
The percentage yield is 79.12%
Explanation:
The first thing we need to calculate here is the theoretical yield of ethyl ethanoate that can be obtained from 20g of ethanol.
Since the mole ratio is 1:1, then this is quite straightforward.
What we need to obtain at first here is the number of theoretical moles of ethanol reacting.
That would be mass of ethanol/molar mass of ethanol
Molar mass of ethanol is 46g/mol
Thus the number of moles is 20/46 = 0.4348 mole
Like it is indicated earlier, since the number of moles are equal from the balanced equation, it also means that 0.4348 mole of ethylethanoate is produced
Now, we need to know the mass of ethyl ethanoate produced
The mass can be calculated by multiplying the number of moles by the molar mass
The molar mass of ethyl ethanoate is 88g/mol
So the mass of it produced = 0.4348 * 88 = 38.2624 or let’s just say 38.26
Thus, the percentage yield will be;
Actual yield/Theoretical yield * 100%
From the question, our actual yield is 30.27g while our calculated theoretical yield is 38.26g
= 30.27/38.26 * 100% = 79.12%
MY ELEMENT IS SODIUM
1. Summarize the physical and chemical properties of the element you selected.
2. In the lesson, many models were used to depict the atom. How did these models help you understand atomic structure?
3. How do protons, neutrons, and electrons differ in terms of their electrical charges and locations within the atom?
4. Describe the four fundamental forces. Which of these forces are involved in chemical bonding?
Please answer these questions or at least one.
Answer:
Explanation:
1. The element you selected is Sodium. some of the physical properties are
i. Sodium has a strong metallic lustre
ii. Sodium are usually silver white in color
iii. Sodium is soft it can be cut with knife
iv. Sodium are malleable and ductile.
v. Sodium conduct electricity
Sodium belong to group 1 elements which are called Alkali metals. Sodium have one valency electron and it gives this electron easily during bonding . This is one reason sodium and other alkali metals are very reactive. Sodium can instantly be oxidized by water. Sodium has a relative atomic mass of approximately 23 amu.
2. There are various models that describe atoms .This models includes John Dalton models, J.J Thompson model, Ernest Rutherford model, Bohr's models etc. This models made us understand the role and location of each sub atomic particles. The models shed more light on subatomic particles like electron which revolve around the nucleus. It provide more information on what contribute to the weight of an atom.
3. The proton , neutron and electron are subatomic particles of an atom. The proton and the neutron are located at the nucleus of an atom. The proton and neutron contributes majorly to the weight of an atom. The proton is positively charge while neutron has no charge.
Electron is found to move around the nucleus in cloud. The electron is negatively charge. The electron determines bonding of atoms. An atom is electrically neutral if the number of proton is equal to the number of electron.
4. The four fundamental forces includes weak nuclear forces , strong nuclear forces , gravity and electromagnetic forces.
Weak nuclear forces is responsible for particle decay .Nuclear forces don't play a role in chemical reaction . If they are involve in a reaction it becomes nuclear reaction not chemical reaction.
Strong nuclear forces causes a strong nuclear interaction and it is the strongest among the 4 fundamental forces. This strong force only operate when subatomic particles are much closer to each other.
Gravity force is too weak to affect chemical reaction much. The gravity forces involves the interaction between two objects with energy and mass.
The electromagnetic force act between charged particles like negatively charged electron and positively charged proton. Electromagnetic force is the most important force in chemical bonding as it depends on the arrangement of atoms and the state of their electron. Electromagnetic forces exist in various forms like the covalent bond, metallic, ionic , dipole dipole, hydrogen bonds and many more. The major force involve in chemical bonding is the electromagnetic force.
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
