Answer:
[tex]{ \bf{ 2 Cl{}^{ - } _{(aq)} + Pb {}^{2 + } _{(aq)} \: ⟶ \: PbCl _{2(s)}}}[/tex]
You're a dentist and want your patients to have the cleanest smiles possible. You're not sure which toothpaste to recommend and decide to design an
experiment to determine which toothpaste gives the brightest and whitest smile.
1) What variables would you need to control in your
experiment?
2) Which variable would you change to determine which toothpaste is best?
3) What is the measurable outcome for this experiment?
d) What would the procedure be for your experiment? Please help me to answer this questions:(
Answer:
Why do you need good toothpaste?
Explanation:
Answer:
Do this yourself smh this isnt what the wesite is for
Explanation:
What is the equilibrium expression for the reaction below?
2Na(s) + 02) Na2O2,(s)
Answer:
[tex]{ \tt{k _{c} = \frac{[Na_{2} O _{2} ]}{[Na] {}^{2} [O _{2} ]} }}[/tex]
When heat is applied to 80 grams of CaCO3, it yields 39 grams of B. Determine the percentage of the yield.
The question is incomplete, the complete question is:
When heat is applied to 80 grams of CaCO3, it yields 39 grams of CaO Determine the percentage of the yield.
CaCO3→CaO + CO2
Answer: The % yield of the product is 87.05 %
Explanation:
The number of moles is defined as the ratio of the mass of a substance to its molar mass.
The equation used is:
[tex]\text{Number of moles}=\frac{\text{Given mass}}{\text{Molar mass}}[/tex] ......(1)
We are given:
Given mass of [tex]CaCO_3[/tex] = 80 g
Molar mass of [tex]CaCO_3[/tex] = 100 g/mol
Putting values in equation 1, we get:
[tex]\text{Moles of }CaCO_3=\frac{80g}{100g/mol}=0.8mol[/tex]
For the given chemical reaction:
[tex]CaCO_3\rightarrow CaO+CO_2[/tex]
By stoichiometry of the reaction:
If 1 mole of [tex]CaCO_3[/tex] produces 1 mole of CaO
So, 0.8 moles of [tex]CaCO_3[/tex] will produce = [tex]\frac{1}{1}\times 0.8=0.8mol[/tex] of CaO
We know, molar mass of [tex]CaO[/tex] = 56 g/mol
Putting values in above equation, we get:
[tex]\text{Mass of CaO}=(0.8mol\times 56g/mol)=44.8g[/tex]
The percent yield of a reaction is calculated by using an equation:
[tex]\% \text{yield}=\frac{\text{Actual value}}{\text{Theoretical value}}\times 100[/tex] ......(2)
Given values:
Actual value of the product = 39 g
Theoretical value of the product = 44.8 g
Plugging values in equation 2:
[tex]\% \text{yield}=\frac{39 g}{44.8g}\times 100\\\\\% \text{yield}=87.05\%[/tex]
Hence, the % yield of the product is 87.05 %
name the gas which is formed when coal is heated in the absense of air
Answer:
Coke
Explanation:
A solid fuel formed by heating coal in the absence of air is coke. Coke is black colored, tough porous substance. It is pure carbon.
An aqueous sodium acetate, NaC2H3O2 , solution is made by dissolving 0.395 mol NaC2H3O2 in 0.505 kg of water. Calculate the molality of the solution.
Answer: The molality of [tex]NaC_2H_3O_2[/tex] solution is 0.782 m
Explanation:
Molality is defined as the amount of solute expressed in the number of moles present per kilogram of solvent. The units of molarity are mol/kg. The formula used to calculate molality:
[tex]\text{Molality of solution}=\frac{\text{Moles of solute}}{\text{Mass of solvent (in kg)}}[/tex] .....(1)
Given values:
Moles of [tex]NaC_2H_3O_2[/tex] = 0.395 mol
Mass of solvent (water) = 0.505 kg
Putting values in equation 1, we get:
[tex]\text{Molality of }NaC_2H_3O_2=\frac{0.395mol}{0.505kg}\\\\\text{Molality of }NaC_2H_3O_2=0.782m[/tex]
Hence, the molality of [tex]NaC_2H_3O_2[/tex] solution is 0.782 m
3. Which best describes the definition for the atomic mass of an element?
A. It is a ratio based on the mass of the carbon-12 atom.
B. It is the sum of the protons. And neutrons in one atom of the element.
C. It is twice the number of protons in one atom of the element.
D. It is a weighted average of the masses of an element’s isotopes.
Answer:
B
Explanation:
Its the sum of the protons and neutrons.
What mass of Na2SO4is needed to make 2.5 L of 2.0 Msolution? (Na = 23 g; S = 32 g; O = 16 g)
a.356 g
b.284 g
c.710 g
d.178 g
Answer:
mass (g) needed = 710.2 grams Na₂SO₄(s)
Explanation:
Needed is 2.5 Liters of 2.0M Na₂SO₄; formula wt Na₂SO₄ = 142.04g/mol.
mass (grams) of Na₂SO₄(s) = Molarity needed x Volume needed in Liters x Formula Wt of solute
mass (grams) of Na₂SO₄(s) = (2.5L)(2.0M)(142.04g/mol) = 710.2 grams Na₂SO₄(s)
Mixing: Transfer 710.4 grams Na₂SO₄ into mixing vessel and add water-solvent up to but not to exceed 2.5 Liters total volume. Mix until dissolved.
Gives 2.5 Liters of 2.0M Na₂SO₄(aq) solution.
How much energy would be produced from the reaction of 2.40 moles hydrogen with 3.95 moles chlorine? ___ H2 + ___ Cl2 ___ HCl ΔH = -554 kJ
Answer:
How much energy would be produced from the reaction of 2.40 moles hydrogen with 3.95 moles chlorine?
[tex]H_2 + Cl_2 -> 2HCl , deltaH = -554 kJ[/tex]
Explanation:
Given,
2.40 moles hydrogen reacts with 3.95 moles chlorine.
From the balanced chemical equation,
1mol. of H2 reacts with 1mol. of Cl2
then,
2.40mol. of H2 reacts with ----?mol of Cl2
[tex]=>2.40 mol. H2 * \frac{1mol. Cl2}{1mol. H2} \\=2.40 mol. Cl2[/tex]
So, the remaining moles of Cl2 is in excess.
The limiting reagent is--- H2.
1mol. of H2 releases --- 554kJ of energy
then,
2.40mol of H2 releases ---- ?
[tex]=>2.40mol * \frac{554kJ}{1 mol.} \\=1329.6kJ[/tex]
Answer is: deltaH =-1329.6kJ
What must happen for an electron to return to its original energy level from a
higher energy level?
A. It must release photons.
B. It must absorb photons.
C. It must absorb electrical energy.
D. It must emit electrical energy.
Answer:
c
Explanation:
it must absorb electrical energy
SOMEONE HELP chemistry
AMSWER IN THE ATTACHMENT.
How many grams of HNO3 is needed to make 1.5 L of a 3 M solution of HNO3? Show work
Answer:
283.5g
Explanation:
first u need to know the molar mass of hno3 which is 63.01
the g=1.5×3×63.01
g= 283.5
A teacher brings in a cup of iced water and asks students to discuss if the system is exothermic or endothermic . Aida states the system is exothermic , while Alexander states the system is endothermic .
Answer:
C
Explanation:
In thermodynamics, a exothermic system looses heat to the surroundings while an endothermic system absorbs heat from the surroundings.
A system is a part the universe marked off by a specified boundary. The contents of the cup constitutes the system in this case.
The region of space outside the system is called the surroundings. Hence everything outside the cup constitutes the surroundings.
Calculate the change in thermal energy when 2kg of water is heated from 20°C to 80°C.
Answer:
504000 J
Explanation:
Applying,
Δq = cm(Δt)............. Equation 1
Where Δq = change in thermal energy, c = specific heat capacity of water, m = mass of water, Δt = change in temperature.
From the question,
Given: m = 2 kg, Δt = 80-20 = 60°C
Constant; c = 4200 J/kg.°C
Substitute these values into equation 1
Δq = 2(4200)(60)
Δq = 504000 J
Hence the thermal energy is 504000 J
PLEASE HELP ASAP
You have 3 beakers sitting in front of you for a lab, but you forgot to label the beakers. You
do not remember which chemical you put into which beaker, and they are all colourless
solutions. You know that you had hydrogen chloride (HCI), lithium sulfate (Li,SO.), and
Describe two diagnostic tests, including expected results that you could use to identify the
three solutions and allow you to label your beakers
Answer:
put a salt into the beakers
state and explain the trends in the atomic radius and ionization energy for elements Li to Cs.
Explanation:
ionisation energy decrease down the group as the atomic radius increases. Nuclear charge increases. Number of shell increases so the electron will experience more shielding so it would be easier for the atom to loss electron.
In the reaction
Cu° + 2 H2SO4 → CuSO4 + 2 H2O + SO2,
copper is
A) reduced and is the oxidizing agent
B) reduced and is the reducing agent
C) oxidized and is the oxidizing agent
D) oxidized and is the reducing agent
What is the volume of 0.200 mol of an ideal gas at 200. kPa and 400. K?
Use P V equals n R T. and R equals 8.314 StartFraction L times kilopascals over moles time K EndFraction..
3.3256 Liters
See the image I have shared to you above
Answer:
B. 7.2k
Explanation:
took the test ;)
How does increasing temperature increase the number of reactions?
A. It increases the length of time the molecules are together.
B. It increases the collisions that have enough energy to react.
C. It makes the orientation of the molecules not important.
D. It lowers the amount of energy needed for a reaction to occur.
Answer:D. it lowers the amount of evergy needed for a reaction to occur.
Explanation:
a p e x
The concept Arrhenius equation is used here to determine the factor which increases the number of reactions. As the temperature increases, It increases the collisions that have enough energy to react. The correct option is B.
What is Arrhenius equation?An equation which represents the relationship between the activation energy and rate of the reaction is known as the Arrhenius equation. According to this concept, lower the activation energy of a reaction, the higher its rate will be.
The equation is:
[tex]k = A . e^{-} ^{E_{a} } / RT[/tex]
k - Rate constant
A - Frequency factor
Eₐ - Activation energy
R - Gas constant
T - Temperature
When the temperature increases, the energy and speed of the molecules increases which in turn increases the number of effective collisions. If greater the value of frequency of collisions, then value of 'k' will be higher and greater is the number of reactions.
Thus the correct option is B.
To know more about rate of a reaction, visit;
https://brainly.com/question/30546888
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13. If a reaction is endothermic,
a) The temperature increases
b) It takes more energy to break the bonds of the reactants than is released when the bonds in
the products are formed
c) More energy is released when the bonds in the products are formed than is used to break
the bonds in the reactants
d) The same amount of energy is used to break the bonds of the reactants as is
released when the bonds in the products are formed
Answer:
Endothermic reactions are reactions that require external energy, usually in the form of heat, for the reaction to proceed. In order to melt the ice cube, heat is required, so the process is endothermic. Endothermic reactionIn an endothermic reaction, the products are higher in energy than the reactants.
Explanation:
which is an example of the force of attraction between two obects that have mass?
Answer:
gravity
Explanation:
Gravity is an example of the force of attraction between two objects that have mass.
Which method do you think the suspects used to make the coins, additive plating or displacement plating?
Answer:
See explanation
Explanation:
Electroplating is a method used to coat a metal on top of another metal for various purposes.
Additive plating involves the coverage of a metal surface by another metal. To make the coins, the suspects had to coat the required coinage metal on another metal called the base metal so as to produce the coin.
Hence the method used must be additive plating method.
photographers take time-lapse photos of the night sky . one of them is at quarter the other is at the south pole , which photo will show that stars never rise and set. explain
Answer:
| EarthSky
Photographers take star trail photos by pointing their cameras at the sky and leaving the shutter open for long exposures, resulting in an image that ...
https://earthsky.org › tonight › circu...
A TV has a standby current of 0.05 amperes. The voltage going through the TV is 120 volts. Determine the power consumption while the TV is in standby.
Answer:
6 Watts
Explanation:
From the question given above, the following data were obtained:
Current (I) = 0.05 A
Voltage (V) = 120 V
Power (P) =?
Electrical power is defined by the following equation
The power consumption while the TV is in standby can be obtained as follow:
Power (P) = Current (I) × Voltage (V)
P = IV
With the above formula, we can obtain the power consumption while the TV is in standby. This can be obtained as follow:
Current (I) = 0.05 A
Voltage (V) = 120 V
Power (P) =?
P = IV
P = 0.05 × 120
P = 6 Watts
Therefore, the power consumption while the TV is in standby is 6 Watts.
i need help with this asap for brainly
Sodium does not make up these proteins.
HELP! HELP! Calculate the value of ΔS⁰ at 298 K.
Answer:
ΔS⁰ = -181.1J/molK
Explanation:
ΔS⁰ of a reaction is defined as the sum of the entropies of the reactants times its reaction coefficient minus the sum of the entropies of the products times its reaction coefficient. For the reaction in the problem:
ΔS⁰ = 2*S{NaCl(s)} - (2*S{Na(s)}+S{Cl2(g)})
ΔS⁰ = 2*72.1J/molK - (2*51.1J/molK + 223.1J/molK)
ΔS⁰ = -181.1J/molKWhat happens to the particle motion of a substance if the temperature changes?
Answer:
With an increase in temperature, the particles move faster as they gain kinetic energy, resulting in increased collision rates and an increased rate of diffusion. ... With an increase in temperature, the particles gain kinetic energy and vibrate faster and more strongly
Explanation:
Radhe Radhe❤
Give an example of a reaction where the following are involved:
(a) Heat
(b) Light
(c) Electricity
(d) Close contact
(e) Solution
(f) Pressure
(g) Catalyst
Explanation:
everything can be found in the picture
What type of force are you exerting when you lie on a bed?
A. Electric force
B. Magnetic force
C. Compression
D. Tension
Answer:
C. Compression
Explanation:
I'm pretty sure it's compression
Help me with this science question on the middle one..
ChemBonding9. In ammonium chloride NH4Cl, the bonding between NH4+ and chloride ion Cl− is _______.
options:
ionic
polar covalent
nonpolar covalent