Answers
Answer:
Remember
Endo = To EnterExo = To ExitThermic = HeatA sparkler burning is an exothermic reaction
Sparkler burning is an exothermic reaction and so the sign of the ΔH must be negative (–∆H) indicating that heat was released.
Ice melting is an endothermic reaction (+∆H) because the ice absorbs (heat) energy, which causes a change to occur.
Acetone evaporating from skin is an endothermic reaction (+∆H). Because, molecules that are evaporating are absorbing heat. So, evaporation is called endothermic.
Related Questions
Write a net ionic equation for the reaction that occurs when excess hydroiodic acid and nickel(II) sulfide are combined.
Answers
Explanation:
Step 1: Write the balanced "molecular" equation:
[tex]2HI(aq) + NIS (s) → NiI₂(aq) + H₂S(g)[/tex]
Step 2: H₂S is written in molecular form. Consult the solubility and net ionic equation rules on the information page to determine which of the other substances will dissociate:
[tex]2HI(aq) + NIS (s) → NiI₂(aq) + H₂S(g)[/tex]
yes no yes
Step 3: Dissociate all soluble salts, strong acids, and strong bases (except calcium hydroxide). Leave together all "not soluble" salts and weak acids or bases:
[tex] {2H₃O}^{ + } (aq) + {2I}^{ - } (aq) + NiS(s)→ { Ni}^{2 + }(aq) + {2I}^{ - }(aq) + H₂S(g) + 2H₂O(l)[/tex]
Step 4: Cross out "spectator ions" that appear on both sides of the reaction (these ions do not participate in the chemistry) and rewrite the "net" reaction using the smallest possible coefficients:
[tex] {2H₃O}^{ + } (aq) + NiS(s) → { Ni}^{2 + } (aq) + H₂S(g) + 2H₂O(l)[/tex]
12. If you had 375 K, what would the temp be in Celsius?
a. 648°C
c. 500°C
b. 435°C
d. 102°C
Answers
Answer:
As Per Provided Information
Given temperature is 375K
We have been asked to find the temperature in Celcius .
[tex] \boxed{\bf \: {}^{ \circ}C =Given \: Temperature \: in \: k \: - 273}[/tex]
Substituting the given value in above equation and let's solve it
[tex] \qquad \longrightarrow\sf \: {}^{ \circ}C = \: 375 - 273 \\ \\ \\ \qquad \longrightarrow\sf \: {}^{ \circ}C = \: 102[/tex]
Therefore,
Temperature in Celcius will be 102 °CSo, your answer is d) 102°C
Are two atoms of the same element identical?
Answers
Answer: No, two atoms belonging to the same chemical element are not necessarily identical.
Explanation:
I hope that was helpful
**Multiple Choice**
**Q:** When an acid reacts with a metal, what is one of the usual products?
(a) carbon dioxide
(b) water
(c) hydrogen gas (this?)
(d) salt
(e) none of the above
Answers
Answer:
When an acid reacts with a metal, what is one of the usual products?
C) Hydrogen gas
Explanation:
- 2HCI(aq) › ZnCl2(aq) + Ha(g) / was given four different hydrochloric acid solutions, each of had a different molarity. He was curious to see what would en if he put a 5 gram piece of zinc metal into 50 ml of each olution. In which HCI solution would the zinc metal have the est rate of reaction? [ think about how you will compare 5.1 5M HCI LOM HCI 1.5M HCIZn(s) + 2HC|(aq) > ZnCl(aq) + H2(g) Bobby was given four different hydrochloric acid solutions, each of which had a different molarity. He was curious to see what would happen if he put a 5 gram piece of zinc metal into 50 ml of each HI solution. In which HI solution would the zinc metal have the quickest rate of reaction? [ think about how you will compare dollars. ] A) .5M HCI B) 1.0M HCI C) 1.5M HCI D) 2.OM HCI
Answers
The rate of reaction between zinc and either HCl or HI will be highest in the 2.0 M solutions since they had the highest concentrations.
How does concentration affect the rate of a reaction?The rate of a reaction increases with increase in concentration of the reactants and decreases with decrease in concentration of the reactants.
The solutions of the HCl and HI that has the highest are those with concentrations of 2.0 M.
Therefore, the rate of reaction between zinc and either HCl or HI will be highest in the 2.9l0 M solutions.
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How much concentrated 12M hydrochloric acid is needed to prepare 100. mL of a 2.0M solution?
Answers
Taking into account the definition of dilution, 16.67 mL of 12 M hydrochloric acid is needed to prepare 100. mL of a 2.0M solution.
Definition of dilutionWhen it is desired to prepare a less concentrated solution from a more concentrated one, it is called dilution.
Dilution is the process of reducing the concentration of solute in solution, which is accomplished by simply adding more solvent to the solution at the same amount of solute.
In a dilution the amount of solute does not change, but as more solvent is added, the concentration of the solute decreases, as the volume (and weight) of the solution increases.
A dilution is mathematically expressed as:
Ci×Vi = Cf×Vf
where
Ci: initial concentration.Vi: initial volume.Cf: final concentration.Vf: final volume.Volume of hydrochloric acid neededIn this case, you know:
Ci= 12 M Vi= ?Cf= 2 MVf= 100 mLReplacing in the definition of dilution:
12 M× Vi = 2 M× 100 mL
Solving:
Vi = (2 M× 100 mL)÷ 12 M
Vi= 16.67 mL
In summary, 16.67 mL of 12 M hydrochloric acid is needed to prepare 100. mL of a 2.0M solution.
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Please help me on all of them!!
Answers
(1) The number of moles of nitrogen trihydride produced is 3.63 moles.
(2) The molar ratio not represented is 2 moles of N₂ = 3 moles of NH₃.
Chemical reaction of Nitrogen and hydrogen
The balanced chemical reaction of Nitrogen and hydrogen is given in the equation below;
N₂ + 3H₂ → 2NH₃
From equation above;
3 moles of H₂ --------------------> 2 moles of NH₃
5.45 moles of H₂ ----------------> ? moles of NH₃
= (5.45 x 2) / 3
= 3.63 moles of NH₃
Molar ratio not represented in the above balanced equationFrom the equation above, we have the following molar ratios
2 moles of NH₃ = 3 moles H₂1 mole of N₂ = 2 moles of NH₃ 3 moles H₂ = 1 mole of N₂Thus, the only molar ratio not represented in the balanced chemical equation of Nitrogen and hydrogen gas is 2 moles of N₂ = 3 moles of NH₃.
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Identify each compound as an electrolyte or a nonelectrolyte.
MgCl, (magnesium chloride)
CH, On (sucrose table sugar)
H, SO. (sulfuric acid)
DONE
Answers
The following solutions are electrolytes/non electrolytes;
magnessium chloride- electrolytesucrose - non electrolytesulfuric acid - electrolyteWhat is an electrolyte?An electrolyte is a substance that conducts electricity in solution. An electroyte must be able to dissociate into ions. It is these ions that are the charge carriers in solution.
Now let us define which of these are electrolytes;
magnessium chloride- electrolytesucrose - non electrolytesulfuric acid - electrolyteLearn mlore about electrolyte : https://brainly.com/question/27132799
Answer:
A B A
Explanation:
1. Marie left her briefcase at home and had to return to get it. At which point did she turn back around to go home?
Answers
Answer:
She turned back at the point at which she forgot she left her briefcase. If this isn't the correct answer, please be more specific in the question.
Explanation:
À chemist reacted 17.25 grams of sodium metal with an excess amount of chlorine gas. The chemical reaction that occurred is showr
Na + ch2- Nacl
If the percentage yield of the reaction is 88%, what is the actual yield? Show your work, including the use of stoichiometric calculations and conversion factors.
Answers
Answer:
Actual yield is 38.57
Explanation:
Percentage yield = Actual yield / theoretical yield X 100
Percent yield x theoretical yield / 100 = actual yield
Write the balanced chemical equation:
2Na + CI2 = 2NaCI
Given is 17.25 g Sodium metal (limiting reactant) with excess being chlorine gas
Percent yield is 88%
Mole of Na = 17.25 g / 22.98 = 0.750
Calculate the Theoretical Yield to solve for Actual Yield
Theoretical yield = 0.75 x molar mass of NaCI
Theoretical yield = 0.75 x 58.44 = 43.83 g
When plugged into the original percentage yield formula:
Actual yield = 88 x 43.83 / 100 = 38.57 g
1. Which trait is most likely to be passed on to its organism’s offspring?
Answers
Answer:Evolution
Evolution is the process by which populations of organisms change over generations. … If a trait is advantageous and helps the individual survive and reproduce, the genetic variation is more likely to be passed to the next generation (a process known as natural selection).
Which statement is true about the Group 1 metals?
a
They are the most reactive metals in the periodic table.
b
They all have one shell or ring.
c
These metals do not conduct electricity well.
d
The metals of the group are called halogens.
Answers
Answer:
The metals of the group are called halogens.
Explanation:
hope it works if not im very sorry for wasting ur time :)
What is the mass of 89.6 L of NH3(g) at STP?
Please help I don’t understand!
Answers
Answer:
68g
Explanation:
GMM of NH^3=14+3=17g
Mass =mole×GMM=4×17=68g
hope this helps<33 :)
Which molecule has a trigonal planar shape?
Answers
Answer:
Structure of boron trifluoride, an example of a molecule with trigonal planar geometry.
Explanation:
Which of the following scenarios best describes separation by distillation?
A sample of ocean water is boiled in a glass flask. A solid remains in the flask, and a hot gas flows
into a cooling chamber. When the as cools enough, it condenses back into a liquid in a separate flask.
O a stip of paper with a sample of ink is placed in a jar. The liquid runs up the paper, resulting in
colored bars running up in a line.
O A funnel and porous paper are used to separate solids in a sample of dirty water from the liquid.
O Aliquid sample is spun quickly in a centrifuge. A layer of solid forms on the bottom of the test tube
over time.
Answers
into a cooling chamber. When the gas cools enough, it condenses back into a liquid in a separate flask.
experimental evidence indicates that the nucleus of an atom
Answers
The nucleus of an atom is positively charged and contains most of the mass if the atom.
What is an atom?An atom is the smallest particle of a an element that can take part in a chemical reaction.
Atoms are made up of other smaller sub-particles which are:
neutrons which are neutral protons which are positively charged electrons which are negatively chargedThe protons and neutrons are found in the nucleus of an atom
The electrons are found regions around the nucleus.
Due to the positive charge of the protons, the nucleus of an atom are positively charged and is massive.
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pH of a 4.5x10-6 M solution of HCl.
Answers
[tex]\text{pH} = -\log[H^{+}] = - \log[4,5 \times 10^{-6}] = 5.34[/tex]
How many grams of glucose are disolved in 500 ml of a .50% glucose solution
Answers
Answer:
To make 500 ml, you need 5x this amount. 5 x 4.33 g = 17.21 g glucose in a final volume of 500 ml
Explanation:
hope this helps
What is mass? In the shortest way possible
Answers
Answer:
Mass is the quantity of matter in a physical body.
Explanation:
mass bro
Answer:
a coherent, typically large body of matter with no definite shape.
Explanation:
a mass of curly hair
Which statement is an example of competition?
Answers
"I'll win everyone at the camp games this year."
Explanation:
This above statement is an example of competition because it signifies a matter anticipating an upper hand towards some other matter.
The table below lists three characteristics of an atom of an element
Number of protons:10
Number of neutrons:10
Number of Valence Electrons:8
An atom of which element is described by the data in the table?
Answers
Explanation
Neon has 10 protons, and 10 neutrons.
How to find neutrons:
The number of mass minus the number of protons. 20-10=10.
Valence electrons are the number on the last shell of energy level, with is 8.
But a easy way to find it is by looking at the group number, the last group number in case 18 only focus at 8. Questions?
how can you separate sand and water without filter paper
Answers
Answer:
through Decantation
Explanation:
Decantation: Decantation is pouring out of upper clear layer of liquid into another container to separate two immiscible liquids or to separate different substances in a suspension mixture.
Therefore, we could use decantation once the sand particles settle down by gently pouring the water into another container. Once the water is transfered, we'll be left with sand in the bottom of the first container.
Hope that helps...
The average resting heart rate is between
A. 80-90 bpm
B. 90-100 bpm
C. 60-70 bpm
D. 70-75 bpm
Answers
Hope it helps
The average resting heart rate is between is 70- 75 bytes per minute. This include systolic pressure and diastolic pressure. Hence, option D is correct.
What is heart rate?The count of heart beats per unit time is called heart rate. For a normal condition at the resting time the average heart rate is 70 -75 beats per minute.
The heat beats we hear is the impulse from the open and closing of the heart valves. This includes the systolic and diastolic blood pressures. For a normal person at the systolic rate is 120 mm Hg and diastolic rate is 80 mm Hg.
The blood pressure rate is depends on the diet, inheritance and other factors such as age, physical activities, mental situations etc. For a normal person, the average resting heart rate is 70 - 75 bpm.
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How did Darwin study artificial selection in the late 1800's?
A. He studied the animals on the Galapagos Island.
B. He studied selectively bred animals.
C. He studied the animals in a Zoo.
D. He studied animals in the wild.
Answers
A stock solution has a concentration of 1.5 M SO2 and is diluted to a 0.54 M solution with a volume of 0.18 L. What was the volume of the stock solution
Answers
The volume of the stock solution that has a concentration of 1.5 M SO2 and is diluted to a 0.54 M solution with a volume of 0.18 L is 0.065L.
How to calculate volume?The concentration of a solution can be calculated using the following formula:
C1V1 = C2V2
Where;
C1 = initial concentration = 1.5MC2 = final concentration = 0.54MV1 = initial volume = ?V2 = final volume = 0.18L1.5 × V1 = 0.54 × 0.18
1.5V1 = 0.0972
V1 = 0.0972 ÷ 1.5
V1 = 0.065L
Therefore, the volume of the stock solution that has a concentration of 1.5 M SO2 and is diluted to a 0.54 M solution with a volume of 0.18 L is 0.065L.
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How is the temperature affected (increased or decreased) when the iron block is placed in the water?
a. the iron black (temp increase or decrease)
b. the water (temp increase or decrease)
Question 1 options:
Blank # 1
Blank # 2
Answers
Ten grams of water will require --- calories to raise the temperature 1° C.
Answers
Explanation:
Specific heat capacity of water is 1cal/g/∘C. 1 cal heat is required to increase the temperature of 1 g of water by 1∘C. To increase the temperature of 10 g water by 1∘C, 10 calories of heat is required
PLEASE MARK ME BRAINLIEST IF MY ANSWER IS CORRECT PLEASEWhat mass of water will be needed to change its temperature 25°C using 4,532 J of heat
energy?
Answers
The mass of the water that will be needed to change its temperature by 25°C is : 43.33 grams
Given data :
Energy = 4532 J
Change in temperature = 25°C
Cw = 4.184 J/gk
Determine the mass of water needed
We will apply the formula below
Q = mCwΔt ---- (1 )
4532 = m * 4.184 * 25
therefore :
m = 4532 / 104.6
= 43.33 grams
Hence we can conclude that the mass of water needed to change the temperature by 25°C is 43.33 grams
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The instantaneous rate data in Table 3 were obtained for
the reaction H2(g) + 2NO(g) →H2O(g) + N2O(g) at a
given temperature and concentration of NO. How does
the instantaneous rate of this reaction change as the
initial concentration of Hy is changed? Based on the
data, is [Hz] part of the rate law? Explain.
Answers
Answer:
A) As the initial concentration of H₂ is increased, the reaction rate also increases.
B) Yes, [H₂] is part of the rate law.
Explanation:
For the reaction:
[tex]\displaystyle \text{H$_2$}_\text{(g)} + 2\text{NO}_\text{(g)} \longrightarrow \text{H$_2$O}_\tex{(g)} + \text{N$_2$O}_\text{(g)}[/tex]
The rate law will have the form:
[tex]\displaystyle \text{Rate} = k\left[\text{H$_2$}\right]^n\left[\text{NO}\right]^m[/tex]
Where n and m are the respective order of reactions.
From the table, we can see that as the concentration of H₂ increases, the instantaneous rate also increases.
Therefore, [H₂] is indeed part of the rate law. If it isn't, changing its concentration will have no effect on the instantaneous rate of the reaction.
How many grams of solute are needed to make 2.50 L of a 1.75 M solution of Ba(NO3)2?
Answers
1143.4grams of solute are needed to make 2.50L of a 1.75M solution of Ba(NO3)2. Details about molarity can be found below.
How to calculate mass?The mass of a substance can be calculated by multiplying the number of moles by its molar mass.
However, the number of moles can be calculated by using the following formula:
Molarity = no of moles ÷ volume
no of moles = 1.75 × 2.5
no of moles = 4.38mol
molar mass of Ba(NO3)2 = 261.34g/mol
mass of Ba(NO3)2 = 261.34 × 4.38
mass of Ba(NO3)2 = 1143.4grams.
Therefore, 1143.4grams of solute are needed to make 2.50L of a 1.75M solution of Ba(NO3)2.
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