Answer:
1. iodide ion into neutral iodine
2. blue-black
3. neutral iodine into iodide ion
4. clear
Explanation:
The function of hypochlorite in iodine titration is to oxidize the iodide ion into iodine molecule as shown below;
ClO-(aq) + 2H+(aq) + 2I-(aq) ---------> 6 I2(l) + Cl- (aq)+ H2O(l)
The addition of starch to iodine leads to the formation of a starch iodide complex which has a blue black colour.
the titrant, thiosulfate, reduces neutral iodine into iodide ion as shown below;
I2 + 2S2O32- → 2I- + S4O62-
At end point, the solution becomes clear again.
hello guys pls help me!about the importance of a chemical compound !pls i need five point
Answer:
Chemical structure determines the molecular geometry of a compound by portraying the spatial arrangement of atoms and chemical bonds in the molecule. This provides chemists with an important visual representation of a chemical formula.
What mass of NaCrO2 can be obtained from the reaction of 7.40g Cr(OH)3 with 7.60g NaOH in the following reaction: CrOH3+NaOH==>NaCrO2+2H2O
Explanation:
7.60 g of NaOH = 7.6/40 = 0.19 moles.
Reaction is 1:1 so NaOH in excess and Cr(OH)3 is limiting reactant.
You will get maximum of 0.0718 moles of NaCrO2 which is 0.0718*107 = 7.69 g
The mass of NaCrO₂ that can be obtained from the reaction is 14.92 grams.
To determine the mass of NaCrO₂ obtained, we need to calculate the molar mass and stoichiometry of the reaction.
Calculate the molar mass of Cr(OH)₃ and NaOH:
Molar mass of Cr(OH)₃ = 52.00 g/mol (chromium: 52.00 g/mol, oxygen: 16.00 g/mol, hydrogen: 1.01 g/mol)
Molar mass of NaOH = 39.99 g/mol (sodium: 22.99 g/mol, oxygen: 16.00 g/mol, hydrogen: 1.01 g/mol)
Determine the limiting reagent:
Convert the mass of Cr(OH)₃ to moles: 7.40 g Cr(OH)₃ * (1 mol / 52.00 g) = 0.1423 mol Cr(OH)₃
Convert the mass of NaOH to moles: 7.60 g NaOH * (1 mol / 39.99 g) = 0.190 mol NaOH
The stoichiometry of the reaction tells us that 1 mol of Cr(OH)₃ reacts with 1 mol of NaOH to produce 1 mol of NaCrO₂.
Compare the moles of Cr(OH)₃ and NaOH to determine the limiting reagent:
Cr(OH)3: 0.1423 mol
NaOH: 0.190 mol
Since Cr(OH)₃ has fewer moles, it is the limiting reagent.
Calculate the mass of NaCrO₂ produced:
The molar mass of NaCrO₂ is 105.00 g/mol (sodium: 22.99 g/mol, chromium: 52.00 g/mol, oxygen: 16.00 g/mol)
The stoichiometry tells us that 1 mol of Cr(OH)₃ produces 1 mol of NaCrO₂.
Therefore, the mass of NaCrO₂ obtained is:
0.1423 mol Cr(OH)₃ * (105.00 g NaCrO₂ / 1 mol Cr(OH)₃) = 14.92 g NaCrO₂
Thus, the mass of NaCrO₂ that can be obtained from the reaction is 14.92 grams.
To learn more about stoichiometry here
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Si tengo 56 gramos de amoniaco gaseoso (NH3) ¿Cuántos moles y moléculas (entidades elementales) podré obtener?
Answer: 56 grams of gaseous ammonia (NH3), has 3.28 moles and [tex]19.80 \times 10^{23}[/tex] molecules.
Explanation:
Given: mass of [tex]NH_3[/tex] = 56 g
Molar mass of [tex]NH_3[/tex] is 17.03 g/mol.
As moles of a substance are its mass divided by the molar mass. Therefore, moles of [tex]NH_3[/tex] are calculated as follows.
[tex]No. of moles = \frac{mass}{molar mass}\\= \frac{56 g}{17.03 g/mol}\\= 3.28 mol[/tex]
According to the mole concept, 1 mole of every substance contains [tex]6.022 \times 10^{23}[/tex] molecules. Hence, number of molecules present in 3.28 moles of [tex]NH_3[/tex] are calculated as follows.
[tex]No. of molecules = no. of moles \times 6.022 \times 10^{23}\\= 3.28 mol \times 6.022 \times 10^{23}\\= 19.80 \times 10^{23}[/tex]
Therefore, we can conclude that 56 grams of gaseous ammonia (NH3), has 3.28 moles and [tex]19.80 \times 10^{23}[/tex] molecules.
How many molecules are in 3.7 g H2O
Explanation:
Find out number of molecules first. To find out number of molecules, first we need to know the number of moles present. The number of moles can be obtained by dividing the weight by molecular mass. The Molecular mass of water is 18. Now, by multiplying the moles with the Avogadro number we can find out the number of molecules. Avogadro number is 6×(10 to the power 23). Hence the final result is 3.7/18 ×6 × ( 10 to the power 23).
Hope this helps, if not I'm very sorry.
It takes 53.0 J to raise the temperature of an 11.0 g piece of unknown metal from 13.0∘C to 24.3 ∘C. What is the specific heat for the metal?
Answer:
51 = ( 8.2/1000)Kg ×S (11.5)
51×1000= 8.2 (11.5)S
S = 51000/94.3
S = 540.8 J/kg K
Explanation:
If you have 4 molecules of FeCl3 and an unlimited supply of NaOH, how
many molecules of NaCl can you produce given the following balanced
equation?
FeCl3 + 3NaOH --> Fe(OH)3 + 3NaCl
Answer:
12 molecules of NaCl
Explanation:
The term "unlimited supply of NaOH" means that NaOH is the reactant in excess hence FeCl3 is the limiting reactant that controls the amount of product formed.
Thus;
From the balanced reaction equation;
1 molecule of FeCl3 yields 3 molecules of NaCl
Hence;
4 molecules of FeCl3 yields 4 * 3/1 = 12 molecules of NaCl
Explain the relationship between forward and reverse
reactions at equilibrium and predict how changing the
amount of a reactant or product (creating a stress) will
affect that relationship.
For example (select one from each underlined section)
If the amount of (reactant or product) increases, the rate of the (forward or
reverse) reaction will increase or decrease) to reach a new equilibrium.
If the amount of (reactant or product) decreases, the rate of the (forward or
reverse) reaction will increase or decrease) to reach a new equilibrium.
If a dynamic equilibrium is disturbed by changing the conditions, the position of equilibrium shifts to counteract the change to reestablish equilibrium. If a chemical reaction is at equilibrium and experiences a change in pressure, temperature, or concentration of products or reactants, the equilibrium shifts in the opposite direction to offset the change. This page covers changes to the position of equilibrium due to such changes and discusses briefly why catalysts have no effect on the equilibrium position.
For example, if the system is changed in a way that increases the concentration of one of the reacting species, it must favor the reaction in which that species is consumed. In other words, if there is an increase in products, the reaction quotient, Qc, is increased, making it greater than the equilibrium constant, Kc.
A chemist needs 0.550 mol selenium for a reaction. What mass of selenium should a chemist use?
*show work and giving brainliest*
Answer:
The chemist would require to use 43.43 grams.
Explanation:
In order to solve this problem we need to know how much do 0.550 moles of selenium weigh. To do that we use selenium's molar mass and multiply it by the given number of moles:
0.550 mol * 78.96 g/mol = 43.43 gThe chemist would require to use 43.43 grams.
Consider the following data on some weak acids and weak bases
acid
Ka
name formula
acetic acid
HCH3CO2
1.8 x10−5
hydrocyanic acid
HCN
4.9 x 10−10
base
Kb
name formula
pyridine
C5H5N
1.7 x 10−9
ammonia
NH3
1.8 x 10−5
Use this data to rank the following solutions in order of increasing pH. In other words, select a '1' next to the solution that will have the lowest pH, a '2' next to the solution that will have the next lowest pH, and so on.
a. 0.1M NaCH3CO2
b. 0.1M NH4Br
c. 0.1M NaBr
d. 0.1M KCN
Answer:
b < c < a < d
Explanation:
The weak acid with the lowest pKa will be the most acidic. In the other way, the conjugate base which the acid is weak will be strong.
The weak base with the lowest pKb will be the most basic. And the conjugate base of the weak base will be a strong acid.
Ka Acetic acid = 1.8x10-5
Ka HCN = 1.9x10-10
Kb pyridine = 1.7x10-9
Kb NH3 = 1.8x10-5
NH4Br is the conjugate base of a weak base. That means is a strong acid.
NH4Br has the lowest pH
NaBr is the conjugate base of a strong acid, HBr. That means NaBr is neutral
The most basic between the conjugate base of the acetic acid, NaCH3CO2 and KCN is KCN because the acetic acid is the stronger acid regard to HCN.
The rank is:
NH4Br < NaBr < NaCH3CO2 < KCN
b < c < a < dIf there are 1.55 x 1024 molecules of hydrogen peroxide (H2O2), what is the mass of the
sample?
Answer:
87.54 g of H₂O₂
Explanation:
From the question given above, the following data were obtained:
Number of molecules = 1.55×10²⁴ molecules
Mass of H₂O₂ =.?
From Avogadro's hypothesis,
6.02×10²³ molecules = 1 mole of H₂O₂
Next, we shall determine the mass of 1 mole of H₂O₂. This can be obtained as follow:
1 mole of H₂O₂ = (2×1) + (2×16)
= 2 + 32
= 34 g
Thus,
6.02×10²³ molecules = 34 g of H₂O₂
Finally, we shall determine mass of H₂O₂ that contains 1.55×10²⁴ molecules. This can be obtained as follow:
6.02×10²³ molecules = 34 g of H₂O₂
Therefore,
1.55×10²⁴ molecules
= (1.55×10²⁴ × 34)/6.02×10²³
1.55×10²⁴ molecules = 87.54 g of H₂O₂
Thus, 87.54 g of H₂O₂ contains 1.55×10²⁴ molecules.
At 47c a gas has a pressure of 140kpa. The gas is cooled until the pressure decreases to 105kpa. If the volume remains constant, what will the final temperature be in kelvin’s? In degrees Celsius
Answer:
The final temperature is equal to 240 K or -33.15°C
Explanation:
Given that,
Initial temperature of the gas, T₁ = 47°C = 320 K
Initial pressure, P₁ = 140 kpa
Final pressure, P₂ = 105 kpa
We need to find the final temperature if the volume remains constant. The relation between temperature and pressure is given by :
[tex]P\propto T[/tex]
or
[tex]\dfrac{P_1}{P_2}=\dfrac{T_1}{T_2}\\\\T_2=\dfrac{P_2T_1}{P_1}\\\\T_2=\dfrac{105\times 320}{140}\\\\T_2=240\ K\\\\T_2=-33.15^{\circ} C[/tex]
So, the final temperature is equal to 240 K or -33.15°C.
A 37.2 g sample of copper at 99.8 °C is carefully placed into an insulated container containing 188 g of water at 18.5 °C. Calculate the final temperature when thermal equilibrium is reached. Assume there is no energy transferred to or from the container. Specific heat capacities: Cu = 0.385 J g-1 °C-1 H2O = 4.184 J g-1 °C-1
Answer:
T₂ = 19.95°C
Explanation:
From the law of conservation of energy:
[tex]Heat\ Lost\ by\ Copper = Heat\ Gained\ by\ Water\\m_cC_c\Delta T_c = m_wC_w\Delta T_w[/tex]
where,
mc = mass of copper = 37.2 g
Cc = specific heat of copper = 0.385 J/g.°C
mw = mass of water = 188 g
Cw = specific heat of water = 4.184 J/g.°C
ΔTc = Change in temperature of copper = 99.8°C - T₂
ΔTw = Change in temperature of water = T₂ - 18.5°C
T₂ = Final Temperature at Equilibrium = ?
Therefore,
[tex](37.2\ g)(0.385\ J/g.^oC)(99.8\ ^oC-T_2)=(188\ g)(4.184\ J/g.^oC)(T_2-18.5\ ^oC)\\99.8\ ^oC-T_2 = \frac{(188\ g)(4.184\ J/g.^oC)}{(37.2\ g)(0.385\ J/g.^oC)}(T_2-18.5\ ^oC)\\\\99.8\ ^oC-T_2 = (54.92) (T_2-18.5\ ^oC)\\54.92T_2+T_2 = 99.8\ ^oC + 1016.02\ ^oC\\\\T_2 = \frac{1115.82\ ^oC}{55.92}[/tex]
T₂ = 19.95°C
very small particles of solids and liquids suspended in air are called
Answer:
aerosols
Explanation:
The number of protons in an atom is known as its atomic
What is the mass in grams of 7.5 mol of C8H18?
Answer:
[tex]\boxed {\boxed {\sf 856.74 \ g \ C_8H _{18}}}[/tex]
Explanation:
To convert from grams to moles, the molar mass is used. These values tells us the grams in 1 mole of a substance. They can be found on the Periodic Table (they are equivalent to the atomic masses, but the units are grams per mole).
We are given the compound C₈H₁₈. Look up the molar masses of the individual elements.
Carbon (C): 12.011 g/mol Hydrogen (H): 1.008 g/molNotice there are subscripts that tell us the number of atoms of each element. We must multiply the molar masses by the subscripts.
C₈: 8(12.011 g/mol)=96.088 g/mol H₁₈: 18(1.008 g/mol)=18.144 g/molAdd these 2 values together to find the molar mass of the whole compound.
C₈H₁₈: 96.088 g/mol +18.144 g/mol=114.232 g/molUse this number as a ratio.
[tex]\frac{ 114.232 \ g \ C_8H_{18}}{1 \ mol \ C_8H_{18}}[/tex]
Multiply by the given number of moles: 7.5
[tex]7.5 \ mol \ C_8H_{18}*\frac{ 114.232 \ g \ C_8H_{18}}{1 \ mol \ C_8H_{18}}[/tex]
The moles of C₈H₁₈ will cancel each other out.
[tex]7.5 *\frac{ 114.232 \ g \ C_8H_{18}}{1}[/tex]
[tex]7.5 *{ 114.232 \ g \ C_8H_{18}}[/tex]
[tex]856.74 \ g \ C_8H _{18}[/tex]
7.5 moles of C₈H₁₈ is equal to 856.74 grams of C₈H₁₈
Pactice 3: How is DNA changed when offspring is produced? Select all true answers.
Answer:
Asexual reproduction produces genetically identical offspring.
Binary fission is a type of asexual reproduction.
Explanation:
Asexual reproduction is that which occurs without gamete participation, ie there is no mixing of genetic material. In this process, a cell or group of them detaches from the body of a living being and gives rise to a new individual.
Individuals arising from asexual reproduction are genetically identical with each other, forming what is called a clone. These individuals will have different genetic heritage only if they undergo gene mutation, that is, alteration in the nitrogen base sequences of one or more DNA molecules.
There are several living beings that reproduce asexually among them, eukaryotes, prokaryotes, unicellular, multicellular, protists, bacteria, plants, animals, among others.
An example of asexual reproduction is binary fission, which consists of dividing a cell into two by mitosis, each with the same genome as the "mother cell" (with the same DNA or genetic material as the "mother cell").
please mark this answer as brainliest
What is the percent yield if 108.40 g O2 reacts with excess NH3 according to the balanced equation below and the actual yield is found to be 203.50 grams of H2O?
4 NH3 + 5 O2 → 4 NO + 6 H2O
Answer:
To express the efficiency of a reaction, you can calculate the percent yield using this formula: %yield = (actual yield/theoretical yield) x 100. A percent yield of 90% means the reaction was 90% efficient, and 10% of the materials were wasted (they failed to react, or their products were not captured).
Explanation:
Describe the three values in a learner-centred curriculum that a teacher can use
to create a pedagogy of care in the classroom.
Answer:
to talk in a way that the class can all understand . help them in thing they are falling . and have a good relashaship.
Explanation:
Introduction: Reaction rates are also influenced by surface area and concentration. The surface area of a solid is a measure of how much of the solid is exposed to other substances. The concentration of a substance is a measure of how many molecules of that substance are present in a given volume. Question: How do surface area and concentration affect reaction rates
Answer:
See explanation
Explanation:
Surface area has to do with the number of solid particles that are exposed at a given time and is capable of colliding with other reactant particles. When more surface area is exposed for reaction, then it means that more particles are likely to collide with each other leading to faster chemical reaction rates. When few particles are exposed for reaction (low surface area) then less collisions occur and the rate of reaction is decreased.
Similarly, concentration refers to the amount of substance present. The greater the amount of substance present, the greater the likelihood of collision between particles and the greater the rate of reaction and vice versa.
Which of the following contains the highest number of electrons?
OA) hydroxide ion
OB) oxonium ion
C) ammonium ion
OD) oxide ion
O E) all of them contains the same number of electrons
helphelp help gell help helpp
Which of the following things is not made of wither fermentation?
Cheese
Yogurt
Bread
Peanut butter
Chocolate
How much does REAL carbon fiber cost ? lets say as big as a piece of paper
Answer:
Today, the average total production cost of “standard modulus” carbon fiber is in the range of $7-9 per pound.
Potassium nitrate, KNO3 , has a molar mass of 101.1 g/mol. In a constant-pressure calorimeter, 13.3 g of KNO3 is dissolved in 213 g of water at 23.00 °C . KNO3(s)−→−−H2OK+(aq)+NO−3(aq) The temperature of the resulting solution decreases to 19.60 °X . Assume that the resulting solution has the same specific heat as water, 4.184 J/(g·°C) , and that there is negligible heat loss to the surroundings. How much heat was released by the solution
Answer:
[tex]Q_{sln}=-3219.25 J[/tex]
Explanation:
Hello there!
In this case, for this calorimetry problem, it is possible for us to infer that the heat of the reaction of dissolution of KNO3 is absorbed by the solution composed by the former and water so that we can write:
[tex]Q_{rxn}=-Q_{sln}[/tex]
Thus, given the mass, specific heat and temperature of the solution, we plug in the data to obtain the heat absorbed, by the reaction:
[tex]Q_{rxn}=-m_{sln}C_{sln}\Delta T _{sln}\\\\Q_{rxn}=-(13.3+213)g(4.184\frac{J}{yg\°C} )(19.60-23.00)\°C\\\\Q_{rxn}=3219.25J[/tex]
Also, we can say the the heat released by the solution was -3219.25 J.
Best regards!
The direct transfer of thermal energy between particles of
matter that are touching is called
Answer:
conduction
Explanation:
4. Given that 4NH3 + 5O2 4NO + 6H2O, if 4.23 x 1022 molecules NH3 were made to react with an excess of oxygen gas, how many molecules of NO would form?
5. If 0.433 moles of sulfur react with 0.500 moles of chlorine, how many moles of disulfur dichloride are produced? Which reactant is the limiting reactant and which is the reactant in excess?
S8(l) + 4Cl2(g) 4S2Cl2(l)
6. How many grams of Fe2O3 are produced when 2.30x10^24 molecules of O2 are reacted?
7. 3.50 g of potassium reacts with water to produce potassium hydroxide and hydrogen gas. Calculate the mass of potassium hydroxide produced. The unbalanced equation is: K + H2O KOH + H2
Please help as much as possible!
Answer:
Explanation:
Given Rxn => 4NH₃ + 5O₂ => 4NO + 6H₂O
Given data => 4.23 x 10²² molecules NH₃ => ? molecules NO
Approach: Convert given value in molecules to moles, solve for moles NO by equation ratios in balanced equation. Finish by multiplying moles of NO by Avogadro's Number (= 6.02 x 10²³ molecules/mole) to obtain molecules of NO.
moles NH₃ = 4.23 x 10²² molecules NH₃ / 6.023 x 10²³ molecules/mole
= 0.0703 mole NH₃
From equation stoichiometry of balanced equation 4 moles NH₃ gives 4 moles NO. Then 0.0703 mole NH₃ => 0.0703 mole NO b/c coefficients are equal in balanced equation.
∴molecules of NO = 0.0703 mole NO x 6.03 x 10²³ molecules NO/mole NO
= 4.23 x 10²² molecules of NO.
The remaining problems can be worked much in the same way. Convert given data to moles (if not already expressed in terms of moles), apply equation ratios to calculate needed substance in moles. Finish by converting calculated moles to desired dimension.
Hints for remaining problems:
Divide given moles of reactant substances by respective coefficients, the smaller value is the limiting reactant. Work problem based on moles (not the divide value. That's just for ID of Limiting Reactant). All other reactants will be in excess.
for problem 5 ...
Given 8S(l) + 4Cl₂(g) => 4S₂Cl₂(l)
Given: 0.433mole 0.500mole
LR 0.433/8 0.500/4
= 0.054 = 0.125
Limiting Reactant => Sulfur
Work problem from given 0.433 mole sulfur. Cl₂ will be in excess on completion of rxn.
Summary:
- convert data to moles
- divide mole values calculated by respective coefficient => smaller value is limiting reactant.
- use mole ratios to determine results, NOT the divided by value <=> this is only for ID of limiting reactant.
If ya need more, put question in comments. I'll get it. Now, If you do need additional input, before I do I will ask if you followed the hint suggestions, and your calculation results. Good luck :-)
The x-intercept shows us where the temperature can be no lower, defined as absolute zero. Absolute zero is 0 K. Look at the graph.
Did the line reach (0,0)? If not, how close to absolute zero was the line?
Answer:
someone please answer!:(
Answer:
No, it was 130k way from (0,0).
Explanation:
If 6.75 g of NaOH are dissolved in 50.00 g of water and the temperature increases
from 20.5°C to 47.8 °C.
a. Is this an example of an endothermic or exothermic reaction?
b. What is the q for the reaction? (Remember since the NaOH dissolves in water add the
masses to get the m)
C. How many moles of NaOH are dissolved?
d. What is the AH for the reaction?
Answer: THE STANDARD HEAT OF SOLUTION OF SODIUM HYDROXIDE IN WATER IS -7.68 KJ PER MOLE.
Seeds, flowers, and fruits work together to help a flowering plant reproduce.
Each of these structures is made up of different kinds of tissues specialized
to perform a specific function. What level of body organization does this
group (plants, seeds, and flowers) represent?
A. Organ
B. Cell
C. Cell system
D. Body system. not B
Answer:
I think the body system
Explanation:
Answer:body system
Explanation:
I need to know what the question is asking please help
Answer: What events create the heaviest elements?
I would Select:
Neutron Star Collissions
Supernova
How does an electric field change and influence its surroundings?
Answer:
The electric force acts over the distance separating the two objects. ... The space surrounding a charged object is affected by the presence of the charge; an electric field is established in that space. A charged object creates an electric field - an alteration of the space or field in the region that surrounds it.
Explanation: