Answer:
The temporary hardness of water can be removed by boiling. The bicarbonates get converted to insoluble carbonates and settle down at the bottom.
Calcium bicarbonate -------> Calcium carbonate [insoluble] + Water + Carbon dioxide.
Ca[HCO3]2 -----> Ca CO3 + H2O + CO2
What do you do while drawing a conclusion?
O A. Find a connection between variables
O B. Make a hypothesis
O C. Record observations
D. Make up new data if you need to
Answer:
A. Find a connection between variables
Explanation:
In the scientific method, the first step is to make an observation. To observe means to carefully monitor phenomena with a view to draw general patterns from specific occurrences.
The second step is to draw up a hypothesis; this is a tentative explanation for the observation.
The next step is to perform an experiment to determine the effect of change in one more variables on another variable. The experiment will confirm or disprove the hypothesis.
The last step is to draw a conclusion. In drawing up a conclusion, a scientist finally establishes the relationship between two variables and finds the connection between them.
An ideal gas is contained in a closed assembly with an initial pressure and
temperature of 250 kN/m²and 75°C respectively, If the final volume of the system
is increased 1.8 times and the temperature drops to 18°C, determine the final
pressure of the gas.
Answer: The final pressure is 116kPa or [tex]116kN/m^2[/tex]
Explanation:
The combined gas equation is,
[tex]\frac{P_1V_1}{T_1}=\frac{P_2V_2}{T_2}[/tex]
where,
[tex]P_1[/tex] = initial pressure of gas = [tex]250kN/m^2=250kPa[/tex] [tex](1kN/m^2=1kPa)[/tex]
[tex]P_2[/tex] = final pressure of gas = ?
[tex]V_1[/tex] = initial volume of gas = v ml
[tex]V_2[/tex] = final volume of gas = [tex]1.8\times v=1.8vml[/tex]
[tex]T_1[/tex] = initial temperature of gas = [tex]75^0C=(75+273)K=348K[/tex]
[tex]T_2[/tex] = final temperature of gas = [tex]18^0C=(18+273)K=291K[/tex]
Now put all the given values in the above equation, we get:
[tex]\frac{250kPa\times v}{348}=\frac{P_2\times 1.8v}{291}[/tex]
[tex]P_2=116kPa[/tex]
The final pressure is 116kPa or [tex]116kN/m^2[/tex]
how many oxygen molecules in 2.3x10-⁸g of molecular oxygen
Answer:
6.321 × 10^22
Explanation:
Mass of Oxygen =
3.36
g
Molar mass of oxygen (
O
2
) = 16 x 2 =
32
g
m
o
l
−
Total molecules in oxygen = Mass in grams/Molar mass x
N
A
=
3.36
32
x
6.02
x
10
23
=
6.321
x
10
22
Note:
N
A
(Avagadro's number) =
6.02
x
10
23
Hope it helps...
How many moles are in 8.7 x 104 atoms of oxygen?
28.
Hormones:
A. are released into the interstitium.
B. require target cell receptors to illicit a target cell response.
C. are always proteins.
Only A & B are correct
Answer: I believe that B) require target cell receptors to illicit a target cell response, is the right answer.
Explanation:
2. Which of the following is NOT a function of the saliva?
A. aids in swallowing
B. partially digests starch
C. produces bile
D. softens the food
Explanation:
c . produces bile is not the function of slaiva
Answer:
B. partially digests starch
Think of the different types of reactions you have learned about. How can you tell if they absorb energy or release energy, and at the molecular level, how are they different?
Answer:
? more info
Explanation:
Give users an example of the reactions you've learned about so we can have more of an idea. I'd be glad to help, if you edited your answer, meanwhile I too have homework in need of finishing.
Determine the empirical formula for dioxin (C12H4C14O2)
The empirical formula for dioxin (C₁₂H₄Cl₄O₂) is (C₆H₂Cl₂O).
We can determine the components of a chemical compound by looking at its formula. We can determine the precise number of atoms in a compound's molecule using its molecular formula. The ratio of these components is provided by the empirical formula. It is the compound's molecular formula scaled down to its lowest integer ratio.
Empirical formula for dioxin (C₁₂H₄Cl₄O₂) is (C₆H₂Cl₂O).
To determine the emperical formula:
Step1: Determine the masses.
Step 2: Multiply the grams by the atomic mass to get the number of moles.
Step 3: Subtract the least number of moles from the total number of moles of each element.
Learn more about the Emperical formula with the help of the given link:
https://brainly.com/question/21743699
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why does oxygen and carbon dioxide travel within the seed and the egg
r.
25. An organic compound (A) C3H5N, undergoes reduction with
LiAlHe to give (B), CzHgN. Compound (B) reacts with
chloroform and KOH to give an unpleasant smell. Compound
(B) reacts with sodium nitrite and hydrochloric acid to give
(C), C3H80, which on treatment with conc. H2SOа acid gives
(D) C3H6. (D) on reaction with conc. H2SO4 and subsequent
hydrolysis yield an isomer of (C). Identify A, B, C, D with
proper explanation and chemical reactions.
frivolont metal was
Answer:
A - Nitrile compound
B- AlkylAmine
C- Alcohol
D - Alkene
Explanation:
(A) undergoes reduction to form alkylamine.
(B) is a primary alkyl amine which on carbylamine test gives a foul smell.
(B) reacts with NaNO2 + HCl undergoes diasotisation following which alcohol is produced.
(C) being a alcohol undergoes hydrolysis to give alkene.
(D) On further reaction with H2S04 by the rule of Markownikoff rule it forms a isomer of (C).
What is the percent by mass of water in the hydrate Na2CO3.10H20 (formula mass = 286)?
Calculation: Molar mass of water = 180 % of water = > 180/286*100 = > 62.93%.
Answer: the percent by mass of water in the hydrate Na2CO3.10H20 is 62.93%.
If 1.8 moles of sodium are present, how many moles of zinc are produced?
Answer:
0.9moles of Zn are produced
Explanation:
Based on the reaction:
ZnO + 2Na → Na2O + Zn
1 mole of ZnO reacts with 2 moles of Na to produce 1 mole of Na2O and 1 mole of Zn
For 2 moles of sodium present, 1 mole of Zn is produced (The conversion factor is 2mol Na = 1mol Zn
If 1.8 moles of sodium are present:
1.8mol Na * (1mol Zn / 2mol Na) =
0.9moles of Zn are producedIf a rigid can of volume 10.0 L starts at a temperature of 27 oC and 800.0 torr and is heated to 327 oC, what is the new pressure in torr?
Answer: The final pressure is 1600 torr.
Explanation:
To calculate the final pressure of the system, we use the equation given by Gay Lussac' Law. This law states that pressure of the gas is directly proportional to the temperature of the gas at constant volume.
Mathematically,
[tex]\frac{P_1}{T_1}=\frac{P_2}{T_2}[/tex]
where,
[tex]P_1\text{ and }T_1[/tex] are the initial pressure and temperature of the gas.
[tex]P_2\text{ and }T_2[/tex] are the final pressure and temperature of the gas.
We are given:
[tex]P_1=800.0torr\\T_1=27^oC=(27+273)K=300K\\P_2=?\\T_2=327^0C=(327+273)K=600K[/tex]
Putting values in above equation, we get:
[tex]\frac{800.0torr}{300K}=\frac{P_2}{600K}\\\\P_2=1600torr[/tex]
Thus the final pressure is 1600 torr.
In which direction does the wind blow from during a sea breeze
Answer:
Sea breeze moves from the areas of higher pressure on the water in the direction of the areas of lower pressure on land.
Explanation:
Sea breeze moves from the areas of higher pressure on the water in the direction of the areas of lower pressure on land. Whereas, land breeze blows from the areas of higher pressure on land to the areas of lower pressure on water.
Please help for brainliest
Don’t skip and don’t answer if u don’t know.
Answer:
burning wood be a chemical change because it wouldn’t be able to go back to its original form. A physical change would be a broken pencil. The pencil is still a pencil, it’s just a physical change.But if it were burned it would be a chemical change.
Explanation:
ASAP PLS
A 18.7 g piece of aluminum (which has a heat capacity of 0.89 JPC-g) is
heated to 82.4°C and dropped into a calorimeter containing water
(specific heat capacity of water is 4.18 J/gºC) initially at 22.3°C. The final
temperature of the water is 24.3°C. Ignoring significant figures, calculate
the mass of water in the calorimeter. *
Answer:
think I did this before and its V
The hybridization of orbitals on the central atom in a molecule is sp. The electron-domain geometry around this central atom is ________. The hybridization of orbitals on the central atom in a molecule is sp. The electron-domain geometry around this central atom is ________. trigonal bipyramidal octahedral trigonal planar tetrahedral linear
Answer:The electron-domain geometry around this central atom is linear
Explanation:
The hybridization is sp which means the number of electron pairs involved are 2. The electron domain geometry will have two sigma bonds and thus geometry will be linear.
The electron domain geometry will be Trigonal bipyramidal when hybridization is [tex]sp^3d[/tex]
The electron domain geometry will be octahedral when hybridization is [tex]sp^3d^2[/tex]
The electron domain geometry will be Trigonal planar when hybridization is [tex]sp^2[/tex]
The electron domain geometry will be tetrahedral when hybridization is [tex]sp^3[/tex]
A reaction has activation energy of 85kjper mol. What is the effect on the rate of raising the temperature from 20degree to 30 degree
Answer: The rate increases 3 times on raising the temperature from 20degree to 30 degree
Explanation:
According to Arrhenius equation with change in temperature, the formula is as follows.
[tex]ln \frac{k_{2}}{k_{1}} = \frac{-E_{a}}{R}[\frac{1}{T_{2}} - \frac{1}{T_{1}}][/tex]
where [tex]k_2[/tex] = rate constant at temp [tex]T_2[/tex]
[tex]k_1[/tex] = rate constant at temp [tex]T_1[/tex]
[tex]E_a[/tex]= activation energy
R= gas constant
[tex]T_1[/tex]= temperature = [tex]20^0C=(20+273)K=293K[/tex]
[tex]T_2[/tex]= temperature = [tex]30^0C=(30+273)K=303K[/tex]
[tex]ln \frac{k_{2}}{k_{1}} = \frac{-85\times 1000J/mol}{8.314J/Kmol}[\frac{1}{303} - \frac{1}{293}][/tex]
[tex]ln \frac{k_{2}}{k_{1}}=1.15[/tex]
[tex]\frac{k_{2}}{k_{1}}=3[/tex]
Thus rate increases 3 times on raising the temperature from 20degree to 30 degree
an acid based titration was performed. it took 27.45 mL of the base, KOH, to titrate 3.115 g HBr, the acid. what was the molarity of KOH?
Answer:
1.4 M
Explanation:
n(HBr)=3.115/81
so, 3.115/81=0.0385mol
according to the reaction, n(HBr)=n(KOH)=0.038 mol
C(KOH)=n/V=0.0385/0.02745
0.0385/0.02745 =1.4 M
in short the answer is 1.4 M (molarity)
Describe two signs that show that a chemical reaction happens when magnesium
burns in air.
Answer:
When magnesium burns in air, the oxygen in the air reacts with magnesium metal to produce magnesium oxide.
Magnesium burns in oxygen present in the air to produce magnesium.
What volume would 9.23 moles of oxygen gas occupy at 825 mmHg and 45 C
Answer:
Explain:- 22.4L Imol Page 10 Many gas law problems involve calculating the volume of a gas produced by the reaction of volumes of other gases. The problem solving strategy that we have used throughout your chemistry course is still the same. 10.
The volume would 9.23 moles of oxygen gas occupy at 825 mmHg and 45 C 22.4L.
What is an ideal gas law ?According to the Ideal Gas Law, all gases contain the same number of molecules at the same temperature, pressure, and volume (but not the same mass).
When the temperature and pressure are close to the point of transforming into a liquid or solid, the Ideal Gas law does not apply.
There are four governing assumptions for a gas to be "ideal": The volume of the gas particles is insignificant. The gas particles are all the same size and have no intermolecular forces with one another. According to Newton's Laws of Motion, the gas particles move at random.
Given :
Volume = ?
Number of moles = 9.23 moles
Temperature = 318K
Pressure = 825 mmHg = 1.08 atm
By an ideal gas equation
PV = nRT
V = nRT/ P
= 9.23 × 0.0821 × 318 / 1.08
= 22.4L
Thus, The volume would 9.23 moles of oxygen gas occupy at 825 mmHg and 45 C is 22.4L.
To learn more about an ideal gas law, follow the link;
https://brainly.com/question/28257995
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Whats the name?!?!?!??!?!?!?!?!?!?!!?!?!?!??!?!?!?!
HNO3 + Sn + H2O → H2SnO3 + NO
By algebraic method pls
Answer:
3Sn + 4HNO3 + H2O → 3H2SnO3 + 4NO
Give the formulas for the following
Lithium oxide
Iron(III) nitrate
Aluminum oxide
Copper (II) chloride
Zinc (II) sulfate
Li2O
Fe(NO3)3
Al2O3
CuCl2
ZnSO4
All you have to do here is make sure your charges are balanced when you write the compound. For example, Iron (III) has a +3 charge, and nitrate has a -1 charge. You need 3 nitrates to match that charge, hence Fe(NO3)3.
a sample of oxygen has its absolute temperature halved while the pressure of the has remained constant. if the initial volume is 400ml, what is the final volume?
Answer: 200mL
Explanation:
this type of air pressure is associated with warm air rising
Areas where the air is warmed often have lower pressure because the warm air rises. These areas are called low pressure systems. Places where the air pressure is high, are called high pressure systems. A low pressure system has lower pressure at its center than the areas around it.
A 7.00 g sample of NaCl was dissolved in enough water to give 250 mL solution.
What is the molarity of the solution?
Answer: The molarity of given solution is 0.476 M.
Explanation:
Given : mass of sample (solute) = 7.0 g
Volume of solution (solvent) = 250 mL
Convert mL into L as follows.
[tex]1 mL = 0.001 L\\ 250 mL = 250 mL \times \frac{0.001 L}{1 mL}\\= 0.25 L[/tex]
Molar mass of NaCl is 58.44 g/mol. Hence, moles of NaCl are calculated as follows.
[tex]No. of moles = \frac{mass}{molar mass}\\= \frac{7.00 g}{58.44 g/mol}\\= 0.119 mol[/tex]
Molarity is the number of moles of a substance present in one liter of solution or solvent.
So, molarity of given solution is calculated as follows.
[tex]Molarity = \frac{no. of moles}{Volume (in L)}\\= \frac{0.119 mol}{0.25 L}\\= 0.476 M[/tex]
Thus, we can conclude that molarity of given solution is 0.476 M.
Which describes how technology has changed society?
A. There is less food available to people.
B. People live longer than they used to
O C. It is more difficult to move goods
O d. It is hard for people to communicate
Answer:
B. People live longer than they used to
Explanation:
None of the other answers are correct.
help. no scam links or blocked.
Explanation:
This is cause of b) Static Electricity
It is also called Electrostatic force combined together.
Hope it helps ya :)
A car is traveling at 20 meters/second and is brought to rest by applying brakes over a period of 4 seconds.What is its average acceleration over this time interval?
Answer: Its acceleration is -5 meters/second2.
Explanation:
