Answer:
3 atoms
Explanation:
there is one calcium and two chlorine
3
A student has a 5.00 gram sample of calcium chloride (CaCl2) solid. How many moles of calcium chloride are
contained in this sample?
Answer: 0.0450 moles of [tex]CaCl_2[/tex]
Explanation:
According to avogadro's law, 1 mole of every substance weighs equal to its molecular mass and contains avogadro's number [tex]6.023\times 10^{23}[/tex] of particles.
To calculate the moles, we use the equation:
[tex]\text{Number of moles}=\frac{\text{Given mass}}{\text {Molar mass}}[/tex]
[tex]\text{Number of moles of} CaCl_2=\frac{5.00g}{110.98g/mol}=0.0450moles[/tex]
Thus there are 0.0450 moles of [tex]CaCl_2[/tex]
Can you think of an example where hydrogen and oxygen combine and release energy with little or no release of heat energy?
When hydrogen and oxygen combine, they form water or hydrogen peroxide, and energy is released in the process.
What are oxygen and hydrogen?
Oxygen and hydrogen are the chemical elements of the periodic table, and they both are gas. Oxygen is the most important gas, which is needed for breathing. It is present at 21% in the atmosphere.
Hydrogen is another gas present in nature. It is the lightest gas, and it has diatomic molecules. It remains gas at normal pressure and temperature, but it becomes liquid at low temperature.
The oxygen and hydrogen readily react and for water, and hydrogen peroxide, the process of reaction of hydrogen and oxygen releases an amount of energy.
Hence, Energy is released during the creation of water or hydrogen peroxide when hydrogen and oxygen mix.
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A 52.9g sample of brass, which has a specific heat capacity of 0.375·J·g^−1°C^−1, is put into a calorimeter (see sketch at right) that contains 100.0g of water. The temperature of the water starts off at 15.0°C. When the temperature of the water stops changing it's 18.4°C. The pressure remains constant at 1 atm. Calculate the initial temperature of the brass sample.
Answer: 90.04°C
Explanation: Calorimeter is a device measures the amount of heat of a chemical or physical process. An ideal calorimeter is one that is well-insulated, i.e., prevent the transfer of heat between the calorimeter and its surroundings. So, the net heat change inside the calorimeter is zero:
[tex]q_{1}+q_{2}=0[/tex]
Rearraging, it can be written as
[tex]q_{1}=-q_{2}[/tex]
showing that the heat gained by Substance 1 is equal to the energy lost by Substance 2.
In our case, water is gaining heat, because its temperature has risen and so, brass is losing energy:
[tex]q_{water}=-q_{brass}[/tex]
Calculating:
[tex]m_{w}.c_{w}.\Delta T=-[m_{b}.c_{b}.\Delta T][/tex]
[tex]100.4.18.(18.4-15)=-[52.9.0.375.(18.4-T)][/tex]
Note: final temperature is the same as the substances are in thermal equilibrium.
Solving:
418(3.4)= - 365.01 + 19.8375T
19.8375T = 1786.21
T = 90.04
The initial temperature for the sample of brass was 90.04°.
It is the highest point in a wave.
Answer:
Crest is the highest point of a wave
Convert 10.0 g of iron (II) sulfate to moles.
please explain how to do this! I don't understand
Explanation:
number of moles =mass /relative molecular mass
n=10g/mr(FeSO4)
N=10/(56+32+16×4)
N=10/152
N=0,066 moles
How can we solve food insecurity while reducing food waste?
o inventory food supplies to avoid overbuying
O donate unused food to food banks
O purchase only as much food as you need
O don't throw scraps in the landfill
Answer:
donate unused food to food banks
Explanation:
Becuse food banks processes food to make very fine particles which is mixed with soil and can be given to the plants
PLEASE HELP PLEASE HELP PLEASE HELP PLEASE HELP PLEASE HELP PLEASE HELP PLEASE HELP PLEASE HELP PLEASE HELP PLEWSE HELP PLEASE HELP ANYBODY!!! CHEMISTRY DUE IN 5 MINUTES!! DIMENSIONAL ANALYSIS
How many moles of O2 are in the sample of 3.6 kilograms of air if 21% of the air is oxygen, O2, by mass?
WILL GIVE BRAINLIEST PLEASE ANYONE WHO KNOWS HOW TO DO MOLE CONVERSIONS AND DIMENSIONAL ANALYSIS
Answer:
23.6 moles
Explanation:
From the question given above, the following data were obtained:
Mass of air = 3.6 Kg
Mass percentage of O₂ = 21%
Number of mole of O₂ =?
Next, we shall convert 3.6 Kg of air to grams (g). This can be obtained as follow:
1 kg = 1000 g
Therefore,
3.6 Kg = 3.6 Kg × 1000 / 1 kg
3.6 Kg = 3600 g
Next, we shall determine the mass of O₂ in the air. This can be obtained as follow:
Mass of air = 3600 g
Mass percentage of O₂ = 21%
Mass of O₂ =?
Mass of O₂ = 21% × 3600
Mass of O₂ = 21/100 × 3600
Mass of O₂ = 756 g
Finally, we shall determine the number of mole of O₂ in the sample of air. This can be obtained as follow:
Mass of O₂ = 756 g
Molar mass of O₂ = 2 × 16 = 32 g/mol
Number of mole of O₂ =?
Mole = mass /Molar mass
Number of mole of O₂ = 756 / 32
Number of mole of O₂ = 23.6 moles
Thus, the number of mole of O₂ in the
sample of air is 23.6 moles
When the number of molecules, atoms, or ions of a particular type (here we consider H ions) is in the hundreds of millions, we can confidently speak of concentrations and analyze an average behavior.
a. True
b. False
Answer:
True.
Explanation:
When the number of molecules, atoms or ions of any element is in the hundreds of millions, we can safely speak of concentrations and analyze a standard behavior, and can even specify the different dilutions used, if there are dilutions. This allows analyzes to be clearly understood by any individual. However, it is not possible to do this if the number of molecules, atoms and ions is very small.
In the laboratory, a general chemistry student measured the pH of a 0.328 M aqueous solution of acetylsalicylic acid (aspirin), HC9H7O4 to be 1.987. Use the information she obtained to determine the Ka for this acid.
Answer: [tex]K_a[/tex] for the acid is [tex]3.34\times 10^{-4}[/tex]
Explanation:
[tex]HC_9H_7O_4\rightarrow H^+C_9H_7O_4^-[/tex]
cM 0 0
[tex]c-c\alpha[/tex] [tex]c\alpha[/tex] [tex]c\alpha[/tex]
Give c = 0.328 M and [tex]pH=1.987[/tex]
[tex]1.987=-log[H^+][/tex]
[tex][H^+]=0.0103[/tex]
[tex][H^+]=c\times \alpha[/tex]
[tex]0.0103=0.328\times \alpha[/tex]
[tex]\alpha=0.0314[/tex]
So dissociation constant will be:
[tex]K_a=\frac{(c\alpha)^{2}}{c-c\alpha}[/tex]
Putting in the values we get:
[tex]K_a=\frac{(0.328\times 0.0314)^2}{(0.328-0.328\times 0.0314)}[/tex]
[tex]K_a=3.34\times 10^{-4}[/tex]
the ph of a naoh solution is 12.05. what is the concentration of [oh-] of the naoh solution? express your answer in standard notation
Answer:
0.01 M
Explanation:
NaOH (sodium hydroxide) is a strong base, so it is completely dissociated into ions in aqueous solution:
NaOH ⇄ Na⁺ + OH⁻
So, we have OH⁻ ions in solution.
From the problem, we have the pH value. The pH is calculated as:
pH = -log [H⁺]
As NaOH is a base, we can also calculate the pOH:
pOH = -log [OH⁻]
Thus. we can use the relation between pH and pOH to calculate the pOH and then use it to calculate [OH⁻]:
pH + pOH = 14 ⇒ pOH = 14 - pH = 14 - 12.05 = 1.95
pOH = -log [OH⁻] ⇒ [OH⁻] = [tex]10^{-pOH}[/tex]= [tex]10^{1.95}[/tex]= 0.0112 M ≅ 0.01 M
Answer:
0.0112
Explanation:
They said that was the answer.
What is the half life of the graphed material?
Answer:
3 hours
Explanation:
To know the the correct answer to the question given above, it is important we know the definition of half-life.
The half-life of a substance is simply defined as the time taken for half the substance to decay.
Considering the diagram given above, the initial mass of the substance is 100 g.
Half of the initial mass = 100 / 2 = 50 g
Now, we shall determine the time from the graph taken to get to 50 g.
Considering the diagram given above, the time taken to get to 50 g is 3 hours.
Therefore, the half-life of the material is 3 hours.
Is anyone good at 10th grade chemistry if so can someone help me please ?
If I have 5 moles of a gas at a pressure of 6.5 atm and a volume of 14 liters, what is the temperature?
PV=nRT
Answer: 190.9K
Explanation:
5.6(14) = 5(.0821)T or (5.6*14)/(5(.0821))
78.4 = 0.4105T
190.9K = T
1. How many molecules are in 4.5 moles?
Answer:
depends on what molecule you are looking for
Explanation:
In one mole of stuff (atoms, molecules, eggses), there are NA individual items of that stuff. So, there are 4.5 × NA BCl3 molecules; i.e. 4.5 × 6.022×1023 ≅ 27×1023 individual molecules of BCl3
On the basis of the information above, a buffer with a pH = 9 can best be made by using
A pure NaH2PO4
B H3PO4 + H2PO4–
C H2PO4– + PO42–
D H2PO4– + HPO42–
E HPO42– + PO43
Answer:
D H2PO4– + HPO42–
Explanation:
The acid dissociation constant for [tex]\mathbf{H_3PO_4 , H_2PO^{-}_4 , HPO_4^{2-}}[/tex] are [tex]\mathbf{7\times 10^{-3}, \ \ 8\times 10^{-8} ,\ \ 5\times 10^{-13}}[/tex] respectively.
[tex]\mathbf{pka (H_3PO_4) = -log (7\times 10^{-3} )=2.2}[/tex]
[tex]\mathbf{pka (H_2PO_4^-) = -log (8\times 10^{-8} )=7.1}[/tex]
[tex]\mathbf{pka (HPO_4^{2-}) = -log (5\times 10^{-13} )=12.3}[/tex]
The reason while option D is the best answer is that, the value of pKa for both
[tex]\mathbf{H_2PO^{-}_4 ,\ \& \ HPO_4^{2-}}[/tex] lies on either side of the desired pH of the buffer. This implies that one is slightly over and the other is slightly under.
Using Henderson-Hasselbach equation:
[tex]\mathbf{pH = pKa + log \Big( \dfrac{HPO_4^{2-}}{H_2PO_4^-} \Big)}[/tex]
The compounds that are used for the formulation of the pH 9 buffer are [tex]\rm H_2PO_4^-\;and\;HPO_4^+[/tex]. Thus, option D is correct.
The buffers are the solutions of acids and base of appropriate pH, that are able to limit the change in pH in the reaction mixture.
Which compound is used for pH 9 buffer?The buffer pH is adjusted with the compounds that has been able to add base or acid to the solution.
For the formulation of buffer of specific pH, the acid and base solutions are required.
The compounds that are used for the formulation of the pH 9 buffer are [tex]\rm H_2PO_4^-\;and\;HPO_4^+[/tex], as they are able to provide acid and base to the solution.
Thus, option D is correct.
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A hydrogen atom is removed from the first carbon atom of a butane molecule and is replaced by a hydroxyl group.
Required:
Draw the new molecule formed.
Answer:
See answer below
Explanation:
In this case, let's draw the butane molecule:
CH₃ - CH₂ - CH₂ - CH₃
According to what the exercise states, we removed an atom of hydrogen from the frist carbon. This could be any of the terminals. I'll grab the first from left to right.
CH₂⁺ - CH₂ - CH₂ - CH₃
When this happens, the atom of carbon is lacking one space and it forms a carbocation.
Followed this step, an hydroxile group replace the atom of hydrogen. The hydroxile is the OH, and when we have an alkane with an OH group in the molecule, we are actually converting this molecule into an alcohol, therefore the molecule formed is:
OH - CH₂ - CH₂ - CH₂ - CH₃Hope this helps
2.)what is the place value of 7 in 970 123 885
3.)in 292.145,what number is in the thousands place?
4.)what is the place value of 9 in 6547.965?
5.)in 476.8976,what is the
value of underline digi?...si number 7 po naka underline.
Answer:
2.place value is 70 000 00
What are a few ways diseases spread?
Answer:Through Direct or indirect contact with an infected person or animal, through air or contaminated food and water.
Explanation:
Why is it necessary to run TLC in a closed container and to have the interior vapor saturated with the solvent? What error is introduced into the determination of an Rf value if the top is left off of the developing chamber?
Answer:
See explanation
Explanation:
Rf value is known as retention factor.The retention factor of a particular material is the ratio of the distance the spot moved above the origin to the distance the solvent front moved above the origin(Harper College).
TLC is carried is out in a closed container and the interior is saturated with the solvent vapor in order to have a maximum resolution between components this prevents solvent from evaporating from the system.
Peradventure the solvent for the separation is partly or wholly lost due to an open container, the Rf value would be lower than the expected value.
Explain the flow of energy needed to bring electrical energy to the city.
Answer:
The electricity that flows to our homes is generated in the power station from here it flows through large transmission line which carry it to substations finally distribution carry electricity from substations to homes schools etc
WHEN YOU SEE A BLUE CAR WHAT COLER IS BEING REFLECTED
Answer:
violet
Explanation:
just violet
oh and you spelled "COLER" wrong, its color or colour if you live somewhere else
how many elements are in 2o2
Answer: hope this helps
Explanation: I’m not sure but after some research here’s what I gathered The molecule has 3 calcium atoms, 2 phosphate atoms and 8 O atoms in it also rate this and pls thank me follow and as as many questions as you need.
Classify each of the following as an example of a mandatory, discretionary, or originator controlled policy, or a combination thereof. Justify your answers.
a. The file access control mechanisms of the UNIX operating system
b. A system in which no memorandum can be distributed without the author's consent
c. A military facility in which only generals can enter a particular room
d. A university registrar's office, in which a faculty member can see the grades of a particular student provided that the student has given written permission for the faculty member to see them.
Answer:
Classifications according to mandatory, discretionary, or originator controlled policy, or a combination thereof:
a. Mandatory
b. Originator
c. Discretionary
d. Mandatory and Originator combined
Explanation:
a) Mandatory control means that access to the UNIX operating system is restricted.
b) Originator controlled policy implies that the memorandum cannot be distributed without the author's consent or permission.
c) Discretionary means that only certain authorized users, for example, generals, can access the particular room.
d) Combined Mandatory and Originator means that while access is restricted to some people, the originator's consent is still required before access can be granted to the faculty member.
Methanol has the formula of CH3OH and can be produced by the reaction of carbon monoxide with hydrogen gas. CO + 2 H2 === CH3OH + heat Using the above chemical reaction, determine how each of the following actions would affect the equilibrium of the system. a. heating the mixture b. adding an excess of carbon monoxide c. removing the methanol as it is formed d. adding a substance that reacts with carbon monoxide
Answer:
See explanation below
Explanation:
Let's answer this by parts.
a) As the reaction is naturally exothermic (Exerts heat), increasing temperature means that the reaction will move forward the direction where its absorbing heat
, so the equilibrium will be favored to the reactant side.
b) In this case, the addition of CO, which is a reactant will favor the reaction to the product side. This is because putting more quantity in the reactants will cause that the equilibrium constant K, increase it's innitial value, and this favors the product side.
c) In this case, it happens something similar to case b. This will cause that the reaction will have to work to cover the loss of methanol, therefore, equilibrium will move to the product side too.
d) In this case, we are adding another substance that reacts with CO, so it means that the other reactant is being removed, therefore, the reaction will work to cover this loss but also to cover the adding of the new substance, causing that the K decrease it's value, so equilibrium will be favored to the reactants side.
Hope this helps
9. The role of an organism in an ecosystemis called alan
O A. habitat
O B. niche
O C. evolution
D. community
What volume (mL) of 0.250 M HNO3 is required to titrate (neutralize) a solution containing 0.276 g of KOH?
Answer:
Volume = 19.68 ml
Explanation:
The equation of the reaction is given as;
HNO3 + KOH ---> KNO3 + H2O
1 mol of HNO3 reacts 1 mol of KOH
Converting 0.276 g of KOH to mol;
Number of moles = Mass / Molar mass
Number of moles = 0.276g / 56.1056 g/mol
Number of moles = 0.00492
Since the mole relationship is 1 = 1;
This means 0.00492 mol of HNO3 reacts with 0.00492 mol of KOH
The relationship between molarity and volume id given as;
Molarity = Number of moles / Volume
Volume = Number of moles / Molarity = 0.00492 mol / 0.250 M
Volume = 0.01968 L
Volume = 19.68 ml
Read: https://kids.britannica.com/kids/article/DNA/390730 (Links to an external site.)
Answer the following questions:
1. What sort of things does DNA determine for a creature? (Think physical traits)
2. Sometimes there are mistakes in DNA, what are these mistakes called? what sort of things can these mistakes cause?
3. What makes up the sides of the DNA structure?
4. There are four different bases in DNA: adenine, thymine, guanine, and cytosine. About how many total pairs do humans have in their DNA?
Answer:
im not doing your whole homework. but ill give you one cent ;>, whats ur paypal
Explanation:
A student adds an alka-seltzer to the Koolaid and stirs. The pH meter now reads 8.3. What was released by the alka-seltzer tablet to cause this change?
Answer:
It released hydroxide ions (OH ¯).
Explanation:
A PH of 8.3 indicates that the solution has become a basic solution.
Now, for us to have a basic solution from the addition of an alka-seltzer to Koolaid, it means the Alka-seltzer released plenty of hydroxide ons (OH¯) to the solution.
50 POINTS
Which of the following correctly describes a compound?
A. The atoms are bonded together, and the compound has different physical and chemical properties than the individual elements.
B. The atoms have no set ratio for how the atoms can combine, and they are not chemically bonded together.
C. The atoms can only combine in fixed ratios, and they retain their individual chemical and physical properties.
D. The atoms retain their individual chemical properties, and they can only be separated from each other by a chemical change.
Answer: A chemical compound can be described as substance composed of atoms from more than one element held together by chemical bonds in a fixed stoichiometric proportion. A compound has different physical and chemical properties from its constituent elements.
For example : compound water is made up of H and O bonded together and it has different properties from O and H.
Thus, among the given options, the one coreectly describing a compound is
a) The atoms are bonded together, and the compound has different physical and chemical properties than the individual elements.
Suppose you want to prepare a buffer with a pH of 4.59 using formic acid. What ratio of [sodium formate]/[formic acid) do you need to make this buffer? Formic acid has a K, of 1.8x10 4 Enter your answer to three significant figures.
Answer:
7.08
Explanation:
To solve this problem we'll use the Henderson-Hasselbach equation:
pH = pka + log[tex]\frac{[A^-]}{[HA]}[/tex]Where [tex]\frac{[A^-]}{[HA]}[/tex] is the ratio of [sodium formate]/[formic acid] and pka is equal to -log(Ka), meaning that:
pka = -log (1.8x10⁻⁴) = 3.74We input the data:
4.59 = 3.74 + log[tex]\frac{[A^-]}{[HA]}[/tex]And solve for [tex]\frac{[A^-]}{[HA]}[/tex]:
0.85 = log[tex]\frac{[A^-]}{[HA]}[/tex][tex]10^{(0.85)}[/tex]=[tex]\frac{[A^-]}{[HA]}[/tex][tex]\frac{[A^-]}{[HA]}[/tex] = 7.08The ratio of [sodium formate] to [formic acid] needed to make the buffer is 7.08
How to determine the pKaEquilibrium constant (Ka) = 1.8×10¯⁴pKa =?pKa = –Log Ka
pKa = –Log 1.8×10¯⁴
pKa = 3.74
How to determine the ratio of [sodium formate] to [formic acid]pH = 4.59pKa = 3.74Ratio of [sodium formate] to [formic acid] =?pH = pKa + Log[sodium formate]/[formic acid]
4.59 = 3.74 + Log[sodium formate]/[formic acid]
Collect like terms
4.59 – 3.74 = Log[sodium formate]/[formic acid]
0.85 = Log[sodium formate]/[formic acid]
Take the anti-log of 0.85
[sodium formate]/[formic acid] = anti-log 0.85
[sodium formate]/[formic acid] = 7.08
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H.w. balance the following equations:
a) Iron + chlorine → Iron (iii) chloride
b) Nitrogen + hydrogen → Ammonia
c) Phosphoric acid + sodium carbonate → sodium phosphate + water + carbon dioxide
d) Nitrogen dioxide + water + oxygen → Nitric acid
Answer:
3iron + chlorine=iron3 chloride
nitrogen +3hydrogen
Answer:
a) Iron + chlorine → Iron (iii) chloride
3fe+cl__fe3cl
b) Nitrogen + hydrogen → Ammonia
2N+3h2------2NH3
c) Phosphoric acid + sodium carbonate → sodium phosphate + water + carbon dioxide
2H3PO3+3Na2CO3-----2Na3PO4+3H2O+3CO2
d) Nitrogen dioxide + water + oxygen → Nitric acid
NO2+H2O+O2--NOH
sorry if mistake