A sample of calcium fluoride was decomposed into the constituent elements. If the sample produced 294 mg of calcium, how many g of fluorine were formed?
Answer:
Approximately [tex]279\; \rm mg[/tex] of fluorine would be produced.
Explanation:
Look up the relative atomic mass of these calcium and fluorine on a modern periodic table:
[tex]\rm Ca[/tex]: [tex]40.078[/tex].[tex]\rm F[/tex]: [tex]18.998[/tex].In other words, the mass of each mole of calcium atoms is (approximately) [tex]40.078\; \rm g[/tex]. Similarly, the mass of each mole of fluorine atoms is (approximately) [tex]18.998\; \rm g[/tex].
Calculate the number of moles of calcium atom that were produced:
[tex]\begin{aligned} &n({\rm Ca}) \\ &= \frac{m({\rm Ca})}{M({\rm Ca})} \\ &= \frac{294\; \rm mg}{40.078\; \rm g \cdot mol^{-1}} \\ &= \frac{0.294\; \rm mg}{40.08 \; \rm g \cdot mol^{-1}}\\ & \approx 7.3357 \times 10^{-3}\; \rm mol\end{aligned}[/tex].
Every formula unit of calcium fluoride, [tex]\rm CaF_2[/tex], contains twice as many fluorine atoms as calcium atoms.
Hence, if the sample contained approximately [tex]7.33570 \times 10^{-3}\; \rm mol[/tex] calcium atoms, it would contain twice as many fluorine atoms:
[tex]\begin{aligned}n({\rm F}) &= 2\, n({\rm Ca}) \\ &\approx 2 \times 7.33570\times 10^{-3}\; \rm mol \\ &\approx 1.4671 \times 10^{-2}\; \rm mol\end{aligned}[/tex].
Calculate the mass of that many fluorine atoms:
[tex]\begin{aligned}& m({\rm F}) \\ &= n({\rm F}) \cdot M({\rm F}) \\ &\approx 1.4671 \times 10^{-2}\; \rm mol \times 18.998\; \rm g \cdot mol^{-1} \\ &\approx 278.72 \times 10^{-3}\; \rm g \\&\approx 279\; \rm mg\end{aligned}[/tex].
279 mg of Fluorine was formed in the decomposition reaction
The equation of the reaction is;
CaF2 -----> Ca + 2F
Mass of calcium formed = 294 mg
Number of moles of Ca in 294 mg = 294 × [tex]10^-3[/tex] g/40 g/mol = 0.00735 moles
From the equation, the products are in ration 1 : 2
Since 1 mole of Ca is to 2 moles of F
0.00735 moles of Ca is to 0.00735 moles × 2 moles/1 mole
= 0.0147 moles of F
Mass of F = 0.0147 moles × 19 g/mol
= 0.279g or 279 mg of F
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This timeline woulchre useful to someone who was writing a report titled
5
Select all the correct answers.
Which sentences describe chemical changes?
The temperature of water rises when heated.
When mixed, water and limestone give off heat.
A mixture of red paint and green paint becomes black.
On adding yellow turmeric to a transparent soap solution, the mixture turns bright red.
When ground into powder, grains of wheat become flour.
Answer: The answers are:
When mixed, water and limestone give off heat.
On adding yellow turmeric to a transparent soap solution, the mixture turns bright red.
1,3,5,7-Cyclooctatetraene, C8H8, is an unusual hydrocarbon in that it reacts with exactly 2 equivalents of potassium to give A, C8H8K2, which can be isolated as a white solid. A exhibits a single proton NMR signal. Draw the structure of A
Answer:
Explanation:
The main assignment here is to provide the structure of A. But before that, let us explain briefly some certain things:
The proton NMR (1H) gives data about the quantity of non-identical protons present in the structure. The resonance frequency is seen regarding the standard compound (0 ppm), which is addressed as a chemical shift. The same protons have equal value of chemical shift.
The protons that are available in a similar environment are addressed as comparable protons and the protons with various conditions are called non-identical protons.
However, from the image below, we can see the reaction of the compound 1,3,5,7-cyclooctatetraene resulting in 2 equivalents of potassium forming an aromatic dianion.
Which is a saturated solution?
A）40g NH4Cl in 100g water at 50°C
B）2g SOz in 100g water at 10°C
C）52g KCl in 100g water at 80°C
D）120g KI in 100g water at 20°C
Answer:
C）52g KCl in 100g water at 80°C
Explanation:
A saturated solution is one that contains as much solute as it can dissolve in the presence of excess solute at that particular temperature.
A solutibility curve is a graph that shows the variability with temperature of the solubility of a solute in a given solvent. A solutibility curve can provide information of whether a solution formed frommthe solute and solvent are saturated or not at a given temperature.
From the solubility curve in the attachment below:
A) A saturated solution of NH₄Cl will contain about 52 g solute per 100 g sat 50 °C. Thus, a solution of 40 g NH₄Cl in 100 g water at 50 °C is an unsaturated solution.
B) A saturated solution of SO₂ at 10°C will contain about 70 g of solute in 100 g of water. Thus a solution of 2g SO₂ in 100g water at 10°C is an unsaturated solution.
C) A saturated solution of KCl at 80 °C will contain about 52 g of solute in 100 g of water. Thus, a solution of 52g KCl in 100g water at 80°C is a saturated solution.
D) A saturated solution of Kl at 20 °C will contain about 145 g of solute in 100 g of water. Thus, a solution of 120g KI in 100g water at 20°C is an unsaturated solution.
In order to determine the answer to a chemistry problem, a student first converted the given percentages to mole by assuming the sample size was 100 grams. Then the student divide by the smallest mole amount of the elements present. Finally the student used the ratios to write a formula. Which of the following best describes the problem the student likely solved?
a. Determined percent composition
b. None of the above
c. Determining molecular formula
d. Determining empirical formula
Answer: d. Determining empirical formula
Explanation:
Molecular formula is the chemical formula which depicts the actual number of atoms of each element present in the compound.
Empirical formula is the simplest chemical formula which depicts the whole number of atoms of each element present in the compound.
Step 1: If percentage are given then we are taking total mass is 100 grams. So, the mass of each element is equal to the percentage given.
Step 2 : convert given masses into moles
Step 3 : For the mole ratio, divide each value of moles by the smallest number of moles calculated
Step 4: The mole ratio gives the empirical formula of the compund.
A helium nucleus with two protons and two neutrons is called a(n)
A. alpha particle
B. beta particle
C. electroscope
D. gamma ray
Clear selection
Answer:
Explanation:
Alpha particles,
________ exercise strengthens skeletal muscle, and ________ exercise strengthens skeletal and cardiac muscle.
a.resistance, aerobic
c.
aerobic, resistance
b.
aerobic, aerobic
d.
resistance, resistance
Answer:
... :-!...................nose...........Which part of the stem transports water to the rest of the plant? A.root cells b. xylem c.bark d. phloem
Answer:
B
Explanation:
Answer:
xylem
Explanation:
What is the atomic mass of hafnium if, out of every 100 atoms, 5 have a mass of 176, 19 have a mass of 177, 27 have a mass of 178, 14 have a mass of 179, and 35 have a mass of 180.0? Answer with 2 decimals
Answer:
178.36 a.m.u
Explanation:
5 have a mass of 176,
5/100 * 176 = 8.8
19 have a mass of 177
19 / 100 * 176 = 33.44
27 have a mass of 178
27 / 100 * 178 = 48.06
14 have a mass of 179
14 / 100 * 179 = 25.06
35 have a mass of 180.0
35 / 100 * 180 = 63
Atomic Mass = 8.8 + 33.44 + 48.06 + 25.06 + 63
Atomic Mass = 178.36 a.m.u
Choose the best answer
1. Gas A diffuses twice as fast as another gas B. If the density of the gas A is 2, the molecular mass of
(a)2
(b) 4
(c) 8
(d) 16
i think it is
(b) 4
:) hope its correct :)
Solution remained colorless.
During the experimentation, the test tube was gently heated in a Bunsen burner flame for 60 seconds. What was the reason for this specific
procedure?
A)
Heating was done to initiate the combustion of the metal in water.
B)
Heating was done to confirm that no chemical reaction would take
place in acid
0
Heating was done to precipitate the chemical change in each test
tube containing water
D)
Heating helped released the hydrogen contained in water
molecules so students would have a positive H+ test.
Convert 2.024 kilocalories to calories I need to know ASAP
Explanation:
kcal = 1000 cal
2.024 Kcal to cal
= 2.024 × 1000
= 2024 cal
#CMIIWQuestion 17 of 20
The reactants of a chemical equation have 1 Satom and 40 atoms. Which
set of atoms must also be found in the equation's products so that the
equation models the law of conservation of mass?
A. 4 S and 40
B. 1 S and 40
C. 1 S and 10
O D. 4 S and 10
Answer:
B) 1S and 40
hope it helps
Answer:
b is ur answer
Explanation:
1S and 4O
How many moles of chlorine atoms are there in 0.5 mol of titanium (III) chloride?
Answer:
it is your answer..... if it is helpful plzz like and comment.....
Chlorine and hydrogen gas react to form hydrogen chloride as shown in the following reaction Cl 2 ( g)+H 2 (g)--->2HCl (g) Given a 7.10 g sample of chlorine (MM =71.0 g/mol) , how many grams of hydrogen chloride (MM =36.5 g/mol) is produced, assuming the reaction goes to completion? a. 7.10 g 6.3.65 9 c. 5,68 g d 7.300
Answer:
it should be 7.300 sorry if I am wrong
Answer:
The answer is 115
Explanation:
Teacher walked me through it.
when forces act in equal and opposite directions the net force is and the object
Answer:
Equal forces acting in opposite directions are called balanced forces. Balanced forces acting on an object will not change the object's motion. When you add equal forces in opposite direction, the net force is zero.
Explanation:
HELP FAST 75 PTS Calculate the amount of heat needed to melt 35.0 g of ice at 0 ºC. must show work
Answer:
It takes 12,000 Joules of energy to melt 35 grams of ice at 0 °C
Explanation:
Good Luck!
Give the reason for the following; 1. Iodimetric titrations are usually performed in neutral or mildly alkaline (pH 8) to weakly acid solution. 2. Iodine solutions are prepared by dissolving I2 in a concentrated solution of potassium iodide. 3. Iodimetric determination of vitamin C is performed rapidly after preparing vitamin C solution
Answer:
Explanation:
blach bal
What happens to the pH when alkali is added to the distilled water?
Adding water to an acid or base will change its pH. ... The acid is becoming less acidic. Similarly, when an alkali is diluted with water the concentration of OH - ions decreases. This causes the pH of the alkali to fall towards 7, making the solution less alkaline as more water is added
Alkali is a chemical that is characterized by reacting with acids to produce salts. When alkali or base are added to the distilled water then pH increases.
What is pH?
The pH has been defined as the concentration of the hyronium or the hydrogen ions that releases when dissolved in water. The concentration of the hydroxide and the hydrogen are the determining factor of the acidic and basic nature.
The acids are characterized by the low pH (below 7) whereas, the basic compounds are characterized by the high pH (above 7). The pH scale is used to measure the pH of the solution.
When an alkali is added to the distilld water then hydroxide ions are relesed resulting in an increase in the basicity of the water sample. The pH range depends on the strong and weak base.
Therefore, the pH increases after ading alkaline solution.
Learn more about pH here:
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Predict the products of the electrolysis of molten nickel(II) iodide. Write an ionic half-equation for the formation of one of these products. products:
ionic half-equation:
Answer:
See explanation
Explanation:
The electrolysis of nickel(II) iodide yields nickel solid and iodine gas.
In the oxidation half equation;
2I^-(aq)-------> I2(g) + 2e
In the reduction half equation;
Ni^2+(aq) + 2e -----> Ni(s)
These are the half equations of the process;
The overall equation is;
Ni^2+(aq) + 2I^-(aq)-------> NiI2
Please help me as soon as possible!!! How many grams of H3PO4 are in a 4 L sample of a 17 M solution?
Answer:
about 6664 grams of hydro phosphoric acid are in a sample of 4 L of 17 M solution
Explanation:
grams of H3PO4 = 4 L | 17 mol | 98 grams H3PO4
| 1 L | 1 mol
A chemistry student is given 4.00 L of a clear aqueous solution at 22°C. He is told an unknown amount of a certain compound X is dissolved in the solution. The student allows the solution to cool to 22 C. The solution remains clear. He then evaporates all of the water under vacuum. A precipitate remains. The student washes, dries and weighs the precipitate. It weighs 0.56 kg.
Required:
Using only the information above, Calculate the solubility of X in water at 22° C. If you said yes, calculate it Be sure your answer has a unit symbol and 2 no .0 it. significant digits.
Answer:
The responses to the given points can be defined as follows:
Explanation:
In point 1:
The answer is "No".
In point 2:
The mass of solute = The mass of precipitate [tex]= 0.56\ kg =0.56\ \times 1000 = 560 \ g[/tex]
Calculating the solubility:
[tex]= \frac{\text{mass of solute in g}}{\text{volume of solution in ml}}\\\\ = \frac{560}{ 4000} \\\\ = 0.14 \ \frac{g}{ml}[/tex]
Which of these 2A elements has the largest atomic radius?
A.beryllium
B.magnesium
C.calcium
D.barium
E.radium
Answer:
E. radium
E. radium
E. radium
Answer:
magnesium is the elwment which has the largest atomic number
Which superpower would you have for the rest of your life?
The ability to fly
Teleportation
Super speed
Super strength
Invisibility
Time travel
Or be normal and have nothing special
time travel is the best option
Rank the following compounds in order of increasing solubility in water. Items (4 items) (Drag and drop into the appropriate area) No more items Items in order most soluble CaO BaO KCI KI
I have tried CaO> BaO > KCl > KI, this is incorrect.
Answer:
CaO < BaO < KCl <KI
Explanation:
Let us remember that the solubility of an ionic substance in water depends on the magnitude of the lattice energy and the hydration energy. If the hydration energy is equal to or is greater than the lattice energy, the substance dissolves in water.
However, the lattice energy depends on the size of the ions. The smaller the ions in the ionic compound, the higher the lattice energy and the lesser the solubility of the ionic compound.
KI has the least lattice energy and the highest solubility in water while CaO has the highest lattice energy and the least solubility in water.
HELPPPPPPPPPPPPPPPPP
Answer:
[tex]2H_{2} + O_{2} --> 2H_{2} O[/tex]
Explanation:
This balanced equation satisfies the law of conservation of mass because when balanced with the proper coefficients (the large numbers appearing to the left of each element or compound), there are the same number and type of atoms on each side. There are four hydrogen atoms and two oxygen atoms in both the reactants and the products.
The diagrams below show the alignment of the Sun, the Moon, and Earth.
Answer:A
Explanation: I learned it from a gizmo
2H2O ---> 2H2O + O 2
The ratio of ducks to chickens in our backyard is 2:3. The total number of ducks and chickens together is 30. If mother gave away 3 chickens to our neighbor, what is the new ratio of ducks to chickens now?
Answer:
4:5
Explanation:
No. of chickens before giving away 3 chickens = 30 x 3/5 = 18
No. of ducks before giving away 3 chickens = 30 - 18 = 12
After giving away 3 chickens,
No. of chickens = 15
No. of ducks = 12
New ratio = 12:15 = 4:5