Answer:
[tex]H_{rxn}=-34.36\frac{kJ}{mol}[/tex]
Explanation:
Hello there!
In this case, according to the given information, it is possible to realize that the heat released by the reaction is used up to heat up the mixture, which means we can write:
[tex]-Q_{rxn}=Q_{sol}[/tex]
Whereas the Q of solution is given by the total mass (3.644+42.054), the specific heat of the solution and the change in temperature; thus, we obtain:
[tex]-Q_{rxn}=(3.644g+42.054g)*4.18\frac{J}{g\°C}*(36.2\°C-27.8\°C)\\\\ Q_{rxn}=-1604.55J[/tex]
Next, by computing the moles of the solute, we can proceed to compute the kJ/mol for the enthalpy of reaction (dissolution):
[tex]n=\frac{3.644g}{78.01g/mol}=0.0467mol\\\\H_{rxn}=\frac{Q_{rxn}}{n}\\\\ H_{rxn}=\frac{-1604.55J}{0.0467mol}*\frac{1kJ}{1000J}\\\\ H_{rxn}=-34.36\frac{kJ}{mol}[/tex]
Best regards!
the first three process involved in water purification can be summarize as
Answer:
Aeration,flocculation,coagulation.
Explanation:
Answer:
.
Explanation:
An unknown compound was found to be soluble in concentrated sulfuric acid; however, the 2,4-DNP, chromic acid, and potassium permanganate gave negative results. The only positive result detected was the ferrous hydroxide test. What is the most likely functional group present in such compound
Explanation:
2,4-DNP is negative: aldehyde and ketone absent
Chromic acid is negative: alcohol absent.
KMnO4 test negative: alkene absent
The only positive result is for Fe(OH)2.
Nitro group-containing compounds react with ferrous hydroxide to give amine and ferric hydroxide red ppt. Hence given compound contains the nitro group (-NO2).
811.68 J of energy are used on a 95g chunk of unknown metal. Calculate the resulting temperature change if the specific heat of the metal is 0.534 J/g*C. oC
Answer:
16 °C
Explanation:
Step 1: Given data
Provided heat (Q): 811.68 JMass of the metal (m): 95 gSpecific heat capacity of the metal (c): 0.534 J/g.°CStep 2: Calculate the temperature change (ΔT) experienced by the metal
We will use the following expression.
Q = c × m × ΔT
ΔT = Q/c × m
ΔT = 811.68 J/(0.534 J/g.°C) × 95 g = 16 °C
Lion 7
Which of the following is a valid science lab safety guideline?
omplete
s out of
Select one:
O a. Do not eat or drink anything while in the lab.
ag
tion
O b. Wear a drawstring hoodie to protect yourself from chemicals.
O c. Wait to clean up any spills until you complete the lab
procedure.
O d. Change the lab procedure if necessary to improve the
experiment.
Check
Answer:
A.
Explanation:
You should NEVER eat or drink anything in a lab area. You never know what chemicals or gases are in the lab, and they can harm you.
Wearing a drawstring hoodie won't protect you from chemicals.
Don't wait to clean up chemicals, immediately get a teacher and clean it up (follow the teachers instructions). You never know what has spilled, and if it is harmful or not, or if there is a certain procedure to clean it up.
Don't change the equipment in the middle of an experiment. This can tamper with your results, and depending on what you are working with, this can be dangerous.
What is the charge that a Phosphorus atom would likely form?
+1
+2
+3
-1
-2
-3
Answer:(b) By referring to a periodic table or table of elements, we see that phosphorus (symbol P) has an atomic number of 15. Thus, each atom has 15 protons. The mass number of the ion is 15 + 16 = 31. Because the ion has 15 protons and 18 electrons (three more electrons than protons), its net charge is 3-
Question 3
Which of the objects on the shelf has the greatest inertia?
10 kg
5 kg
2kg
a
b
2 kg
5 kg
10 kg
С
d
The all have the same inertia
5.36 liters of nitrogen gas are at STP. What would be the new volume if we increased the moles from 3.5 moles to 6.0 moles?
Answer:
[tex]V_2=9.20L[/tex]
Explanation:
Hello there!
In this case, according to the given STP (standard pressure and temperature), it is possible for us to realize that the equation to use here is the Avogadro's law as a directly proportional relationship between moles and volume:
[tex]\frac{V_2}{n_2}= \frac{V_1}{n_1}[/tex]
In such a way, given the initial volume and both initial and final moles, we can easily compute the final volume as shown below:
[tex]V_2= \frac{V_1n_2}{n_1} \\\\V_2=\frac{5.36L*6.0mol}{3.5mol}\\\\V_2=9.20L[/tex]
Best regards!
Worth 100 points plus ill mark brainliest
How many grams of sodium phosphate ( Na₃PO₄ )are required to make 125 milliliters of a 0.240 Molar solution?
4.92
6.48
8.44
12.5
Answer:
4.92 grams of sodium phosphate (Na₃PO₄) are required to make 125 milliliters of a 0.240 M.
Explanation:
Molarity is a measure of concentration that indicates the number of moles of solute that are dissolved in a given volume.
The molarity of a solution is calculated by dividing the moles of the solute by the volume of the solution:
[tex]Molarity=\frac{number of moles}{volume}[/tex]
Molarity is expressed in units [tex]\frac{moles}{liter}[/tex].
In this case:
Molarity= 0.240 Mnumber of moles= ?volume= 125 mL= 0.125 LReplacing in the definition of molarity:
[tex]0.240 M=\frac{number of moles}{0.125 L}[/tex]
Solving:
number of moles= 0.240 M*0.125 L
number of moles= 0.03 moles
Being the molar mass of sodium phosphate 164 g/mole, that is, the mass of one mole of the compound, you can calculate the mass of 0.03 moles using the following rule of three: if 1 mole of the compound has 164 grams, 0.03 moles contains how much mass?
[tex]mass=\frac{0.03 moles*164 grams}{1 mole}[/tex]
mass= 4.92 grams
4.92 grams of sodium phosphate (Na₃PO₄) are required to make 125 milliliters of a 0.240 M.
What needs to be taken into consideration when increasing either the acid or base concentration in order to increase the buffering capacity of a solution?
The more concentrated the buffer solution, the greater its buffer capacity.
What is an acid?An acid is any substance that in water solution tastes sour, changes blue litmus paper to red, reacts with some metals to liberate hydrogen, reacts with bases to form salts, and promotes chemical reactions.
The more concentrated the buffer solution, the greater its buffer capacity.
If the buffer capacity is 10 times larger, then the buffer solution can absorb 10 times more strong acid or base before undergoing a significant change in pH.
Hence, we need to take this into consideration when increasing either the acid or base concentration in order to increase the buffering capacity of a solution.
Learn more about acid here:
https://brainly.com/question/3700851
#SPJ2
Which of the following is the correct definition for electronegativity?
А. The amount of energy to attract or bond electrons
В. The amount of energy required to remove an electron
C. Half the distance between the nuclei of two bonded atoms
D. All of the above correctly explain electronegativity
Answer:
[tex]\color{Blue}\huge\boxed{Question} [/tex]
Which of the following is the correct definition for electronegativity[tex]\color{Blue}\huge\boxed{Answer} [/tex]
А. The amount of energy to attract or bond electronsIn the context of a balanced chemical equation, a____is a number to the lower right of an element or ion within formula and it applies to____. A____is a number to the left of a formula and it applies to_____. Only_____should be added or changed when balancing chemical equations.
Answer:
Explanation:
The preceding chapter introduced the use of element symbols to represent individual atoms. When atoms gain or lose electrons to yield ions, or combine with other atoms to form molecules, their symbols are modified or combined to generate chemical formulas that appropriately represent these species. Extending this symbolism to represent both the identities and the relative quantities of substances undergoing a chemical (or physical) change involves writing and balancing a chemical equation. Consider as an example the reaction between one methane molecule (CH4) and two diatomic oxygen molecules (O2) to produce one carbon dioxide molecule (CO2) and two water molecules (H2O). The chemical equation representing this process is provided in the upper half of Figure 1, with space-filling molecular models shown in the lower half of the figure.
Five identical test tubes are each filled from the following five copper (11) sulfate stock solutions. Which of the following test tubes would appear the lightest blue?
a) Stock solution made form 0.200 moles of CuSO4 dissolved to a total volume of 400 ml
b) Stock solution made form 0.150 moles of CuSO4 dissolved to a total volume of 300 mL
C)Stock solution made form 0.250 moles of CuSO4 dissolved to a total volume of 500 ml
d) Stock solution made form 0.175 moles of CuSO4 dissolved to a total volume of 400 ml
e) Stock solution made form 0.125 moles of CuSO4 dissolved to a total volume of 300 ml
Answer:
deez cutz
Explanation:
did i get it right
2. Given the following equation: 2 KCIO3 ---> 2 KCl + 3 O2
How many moles of O2 can be produced by letting 12.00 moles of KClO3 react?
show work. helppp asap
Answer:
18 moles of O2 can be produced by letting 12.00 moles of KClO3 react
Explanation:
The balanced equation is
2KCIO3 ---> 2 KCl + 3 O2
As per the reaction,
2 mole of KClO3 produces 3 mole of O2 gas
Hence, 12 moles of KClO3 will produce [tex]12*\frac{3}{2} =18[/tex]
Hence, 18 moles of O2 can be produced by letting 12.00 moles of KClO3 react
Muscles and bones work together when muscles move bones through contracting and
relaxing.
A.true
B.false
I think it's true.
Explanation:
Muscles move bones through contracting and relaxing
Which of these is most likely made of pieces of rock that are weathered by water and wind?
O A diamonds
OB sand
OC grass
OD vegetables
Answer:
The answer would be sand.
Explanation:
Sand is weathered down tiny pieces of rock. Sand flows down rivers to shores and slowly builds up to form beaches.
Answer:
The Answer is gonna be B sand
How is water used in society
Answer:
Water can be used for direct and indirect purposes. Direct purposes include bathing, drinking, and cooking, while examples of indirect purposes are the use of water in processing wood to make paper and in producing steel for automobiles. The bulk of the world's water use is for agriculture, industry, and electricity.
Explanation:
Answer:
water is used for drinking, bathing, cooking, agriculture etc
a freshwater stream flows into the ocean as shown in the diagram which statement correctly describes how the stream affects these salinity of the ocean
A- salinity increases because the stream adds salt to the ocean.
B- salinity decreases because the stream adds freshwater to the ocean
C- salinity increases because of stream adds freshwater to the ocean
D- salinity Remains the Same because the stream adds freshwater to the ocean
160 mL of a 37.5 % (m/v) LiNO3 solution
Answer:
60g of LiNO3 are required
Explanation:
Calculate the amount of solute, in grams or milliliters, to prepare...
The percentage mass/volume %(m/v) is defined as the mass in grams of the solute in 100mL of solution
To solve this question we must know that in a 37.5% (m/v) of LiNO3 you have 37.5g of LiNO3 in 100mL of solution.
Thus, to prepare 160mL are required:
160mL * (37.5g / 100mL) =
60g of LiNO3 are requiredthe sum of two number is 50,and their difference is 30.find the sum
Answer:
40 and 10
Explanation:
40 plus 10 is 50 40 minus 10 is 30
Answer:
40 and 10
Explanation:
What volume is occupied by 22.1 g of O2 at 52°C and a pressure of 1.63 atm?
Using the Lewis dot system, show the formation of a covalent bond between
A. Two Br atoms
B. A Br atom and a Cl atom
C. A N atom and three H atoms
D. A C atom and 4 Cl atoms
E. An S atom and 2 H atoms
1. When there is light, photosynthesis can
A. occur, in the chloroplast.
B. not occur, and the stomata will not be open.
C. not occur, and the stomata will be open.
D. occur, in the
mitochondria.
Answer:
A
Explanation:
Answer:
A. occur, in the chloroplast.
Explanation:
Photosynthesis occur in chloroplasts, with the help of sunlight. Where mitochondria help in respiration
how can a scientist make a solution using salt and water?
Answer:
by boiling water and add the salt
Explanation:
because salt dissolves better if mixed with hot water which makes the process faster and effective
PLEASE HELPP!
a 55g block of metal has a specific heat of 0.45 J/g°C. What will be the temperature change of this metal if 450 J of heat energy are added?
Answer:
18.18 C
Explanation:
m=55
C=0.45
Q=450zj
ch.temp=?
Q=mct
450 = (55)(.45)T
450 = 24.75
/24.75 = /24.75 (cancels out)
18.18 is the answer
How do humans influence genetic outcomes in artificial selection and what impacts does this have on society?
Answer:
In artificial selection, humans have the capacity to influence certain characteristics of organisms by selective breeding. One can choose desired parental traits determined by genes, which are then passed on to offspring.
Is vinegar and rubbing alcohol soluble or insoluble?
Which one is not soluble in water Licl, lioh or li3po4
Answer:
li3po4
Explanation:
A watt is
A. 1 cal/s.
B. 1 joule/s.
C. 1 s/cal.
D. 1 s/joule.
Answer:
The answer would be B. 1 joule/s.
Explanation:
The answer is B because the power in general is normally defined as energy over time. Watts are defined as 1 Watt = 1 Joule per second (1W = 1 J/s) which means that 1 kW = 1000 J/s.
Another reason why it's B is because I had the same exact question in class, I took a screenshot of it a day ago:
Hope this helps
A chemist weighed out 7.22 g of silver. Calculate the number of moles of silver she weighed out.
Be sure your answer has the correct number of significant digits.
Answer:
0.067 mole Ag°
Explanation:
Given 7.22 g Ag° = 7.22g Ag/ 107.8g/mol = 0.0670 mole Ag° (3 sig. figs.)
100.00 mL of 0.15 M nitrous acid (HNO2) are titrated with a 0.15 M NaOH solution. (a) Calculate the pH for the initial solution. (b) Calculate the pH for the point at which 80.0 mL of the base has been added. (c) Calculate the pH for the equivalence point. (d) Calculate the pH for the point at which 105 mL of the base has been added.
Answer:
a. pH = 2.04
b. pH = 3.85
c. pH = 8.06
d. pH = 11.56
Explanation:
The nitrous acid is a weak acid (Ka = 5.6x10⁻⁴) that reacts with NaOH as follows:
HNO₂ + NaOH → NaNO₂(aq) + H₂O(l)
a. At the beginning there is just a solution of 0.12M HNO₂. As Ka is:
Ka = [H⁺] [NO₂⁻] / [HNO₂]
Where [H⁺] and [NO₂⁻] ions comes from the same equilibrium ([H⁺] = [NO₂⁻] = X):
5.6x10⁻⁴ = X² / 0.15M
8.4x10⁻⁵ = X²
X = [H⁺] = 9.165x10⁻³M
As pH = -log [H⁺]
pH = 2.04b. At this point we have HNO₂ and NaNO₂ (The weak acid and the conjugate base), a buffer. The pH of a buffer is obtained using H-H equation:
pH = pKa + log [NaNO₂] / [HNO₂]
Where pH is the pH of the buffer,
pKa is -log Ka = 3.25
And [NaNO₂] [HNO₂] could be taken as the moles of each compound.
The initial moles of HNO₂ are:
0.100L * (0.15mol / L) = 0.015moles
The moles of base added are:
0.0800L * (0.15mol / L) = 0.012moles
The moles of base added = Moles of NaNO₂ produced = 0.012moles.
And the moles of HNO₂ that remains are:
0.015moles - 0.012moles = 0.003moles
Replacing in H-H equation:
pH = 3.25 + log [0.012moles] / [0.003moles]
pH = 3.85c. At equivalence point all HNO2 reacts producing NaNO₂. The volume added of NaOH must be 100mL. That means the concentration of the NaNO₂ is:
0.15M / 2 = 0.075M
The NaNO₂ is in equilibrium with water as follows:
NaNO₂(aq) + H₂O(l) ⇄ HNO₂(aq) + OH⁻(aq) + Na⁺
The equilibrium constant, kb, is:
Kb = Kw/Ka = 1x10⁻¹⁴ / 5.6x10⁻⁴ = 1.79x10⁻¹¹ = [OH⁻] [HNO₂] / [NaNO₂]
Where [OH⁻] = [HNO₂] = x
[NaNO₂] = 0.075M
1.79x10⁻¹¹ = [X] [X] / [0.075M]
1.34x10⁻¹² = X²
X = 1.16x10⁻⁶M = [OH⁻]
pOH = -log [OH-] = 5.94
pH = 14-pOH
pH = 8.06d. At this point, 5mL of NaOH are added in excess, the moles are:
5mL = 5x10⁻³L * (0.15mol / L) =7.5x10⁻⁴moles NaOH
In 100mL + 105mL = 205mL = 0.205L. [NaOH] = 7.5x10⁻⁴moles NaOH / 0.205L =
3.66x10⁻³M = [OH⁻]
pOH = 2.44
pH = 14 - pOH
pH = 11.56