Answer:
Ice floats on water because it is less dense than water. When water freezes into its solid form, its molecules are able to form more stable hydrogen bonds locking them into positions. Because the molecules are not moving, they're not able to form as many hydrogen bonds with other water molecules. Ice is a unique substance because it is solid-state — ice — is less dense than its liquid state. Because of this property, ice floats in water. Physical properties are characteristics of a substance. They do not change. Ice floats on water because it is less dense than water. When water freezes into its solid form, its molecules are able to form more stable hydrogen bonds locking them into positions.
If 12.3 grams of a substance burns in air to produce 15.9 grams of a compound, what mass of the air reacted?
Answer:
[tex]m_{air}=3.6g[/tex]
Explanation:
Hello,
In this case, given the law of conservation of mass which states that mass cannot be created nor destroyed, since the produced mass of the compound is 15.9 g and the mass of the initial substance is 12.3 g we obtain the mass of air by applying the following equation:
[tex]m_{reactants}=m_{products}\\\\m_{substance}+m_{air}=m_{product}[/tex]
Thus, solving for the mass of air we obtain:
[tex]m_{air}=m_{product}-m_{substance}\\\\m_{air}=15.9g-12.3g\\\\m_{air}=3.6g[/tex]
Regards.
A chemistry teacher spends 35 minutes grading 1 students lab. They have 153 students who turn in lab papers for each lab. If the class completed 25 labs, how many minutes will the teacher spend grading lab papers? I just need to know how to set up the problem and the answer, thank you!!
Answer:
13,3875 minutes or 2,231.25 hours
Explanation:
153 x 25 = 3,825
person x lab paper = all the lab papers turned in.
35 x 3,825 = 13,3875
minutes x all the lab papers turned in = amount of minutes spent on grading
Which of the following conditions characterizes a system in a state of chemical equilibrium?
a) Reactants are being consumed at the same rate they are being produced.
b) Concentrations of reactants and products are equal.
c) Product concentrations are greater than reactant concentrations.
d) Reactant molecules no longer react with each other.
e) Rate of forward reaction has dropped to zero.
Answer:
a) Reactants are being consumed at the same rate they are being produced.
Explanation:
In a chemical reaction, chemical equilibrium is a state in which there is no change in concentration of the reactant and product. This means that as the reactants are consumed, they are also produced. Same thing with the products; immediately they are formed, they are consumed.
The option that accurately depicts a reaction at equilibrium is;
a) Reactants are being consumed at the same rate they are being produced.
If a urine sample has a mass of 244 g and a volume of 242 mL, what is its density in g/mL?
Answer:
244/242 alright
Explanation:
yesss
Answer:
244/242 or 1.00826446 g/mL
Explanation:
Density can be calculated using the following formula.
d=m/v
where m is the mass and v is the volume.
The mass is 244 grams and the volume is 242 milliliters.
m= 244 g
v= 242 mL
Substitute the values into the formula.
d= 244 g / 242 mL
Divide 244 g by 242 mL.
d= 244/242 g/mL
d= 1.00826446 g/mL
The density is 244/242 or 1.00826446 grams per milliliter.
When the equation Sn + HNO₃ → SnO₂ + NO₂ + H₂O is balanced in acidic solution, what is the smallest whole-number coefficient for Sn?
Answer:
1.
Explanation:
Hello,
In this case, for the given reaction we first assign the oxidation state for each species:
[tex]Sn^0 + H^+N^{5+}O^{-2}_3 \rightarrow Sn^{4+}O_2 + N^{4+}O^{2-}_2 + H^+_2O^-[/tex]
Whereas the half reactions are:
[tex]Sn^0+2H_2O \rightarrow Sn^{4+}O_2 +4H^++4e^-\\\\H^++H^+N^{5+}O^{-2}_3 +1e^-\rightarrow N^{4+}O^{2-}_2+H_2O[/tex]
Next, we exchange the transferred electrons:
[tex]1\times(Sn^0+2H_2O \rightarrow Sn^{4+}O_2 +4H^++4e^-)\\\\4\times (H^++H^+N^{5+}O^{-2}_3 +1e^-\rightarrow N^{4+}O^{2-}_2+H_2O)\\\\\\Sn^0+2H_2O \rightarrow Sn^{4+}O_2 +4H^++4e^-\\\\4H^++4H^+N^{5+}O^{-2}_3 +4e^-\rightarrow 4N^{4+}O^{2-}_2+4H_2O[/tex]
Afterwards, we add them to obtain:
[tex]Sn^0+2H_2O+4H^++4H^+N^{5+}O^{-2}_3 \rightarrow Sn^{4+}O_2 +4H^++4N^{4+}O^{2-}_2+4H_2O[/tex]
By adding and subtracting common terms we obtain:
[tex]Sn^0+4H^+N^{5+}O^{-2}_3 \rightarrow Sn^{4+}O_2 +4N^{4+}O^{2-}_2+2H_2O[/tex]
Finally, by removing the oxidation states we have:
[tex]Sn + 4HNO_3 \rightarrow SnO_2 + 4NO_2 + 2H_2O[/tex]
Therefore, the smallest whole-number coefficient for Sn is 1.
Regards.
Classify each as a physical or chemical change.
Explain each answer.
a) When limestone is heated carbon dioxide and
calcium oxide result.
b) Digesting a candy bar.
c) Copper can be drawn into thin wires.
d) Ripening of fruits.
e) Ice floats on water
Answer:
a) When limestone is heated in a kiln, the calcium carbonate breaks down into calcium oxide and carbon dioxide. This type of reaction is called thermal decomposition. The process is called calcining. ... Slaked lime is used to reduce the acidity of the soil, which helps increase its fertility.
b) Mechanical digestion occurs in the mouth, stomach, and small intestine. Food is chemically changed indigestion when new, smaller substances are formed. These chemical changes are examples of chemical digestion. Chemical digestion begins in the mouth when enzymes in saliva begin to break down carbohydrates.
c) Copper is a ductile metal. This means that it can easily be shaped into pipes and drawn into wires. Copper pipes are lightweight because they can have thin walls. They don't corrode and they can be bent to fit around corners.
d) Ripening of fruits is a chemical change. During ripening the pigment present in the skin of the fruit changes and this can not be reversed back. it is a chemical change as once a fruit ripens it cannot turn raw again.
e) Ice is a unique substance because it is solid-state — ice — is less dense than its liquid state. Because of this property, ice floats in water. Physical properties are characteristics of a substance. They do not change. Physical properties include colour, smell, freezing/melting point, and density.
Which sentence describes a chemical property?
A. Cars that are missing paint can rust over time.
B. A pot of water gets hotter on a burner.
O C. Paper can be cut into smaller pieces.
O D. A pitcher can hold several glasses of water.
Answer:
A. Cars that are missing paint can rust over time shows a chemical property of rusting.
4Fe + 3O² + 6H²O → 4Fe(OH)³.
(Iron) (Air) (Water) (Rust)
Note: The powers in equation should be written below .
Hope it helps.
Sulfur and oxygen form both sulfur dioxide and sulfur trioxide. When samples of these are decomposed, the sulfur dioxide produces 3.52 g oxygen and 3.53 g sulfur, while the sulfur trioxide produces 9.00 g oxygen and 6.00 g sulfur.
Calculate the mass of oxygen per gram of sulfur for each sample and show that these results are consistent with the law of multiple proportions
Answer:
See explanation
Explanation:
For sulphur dioxide;
3.53 g of sulphur combines with 3.52 g of oxygen
1.00 g of sulphur combines with 1.00 × 3.52/ 3.53 = 0.997 g
For sulphur trioxide
6.00 of sulphur combines with 9.00 g of oxygen
1.00 g of sulphur combines with 1.00 × 9.00/6.00 =1.5 g
Ratio of mass of oxygen;
1 : 1.5
The law of multiple proportions states that, if two elements A and B combine to form more than one chemical compounds, then the various masses of element A which combines separately with a fixed mass of element B are in simple multiple ratio.
We can see that the mass of oxygen which combines separately with sulphur in sulphur dioxide and sulphur trioxide are in simple ratio of 1:1.5.
1) What mass of Na2CO3 is required to make 50cc of its seminormal solution?
Answer:
[tex]m=1.325gNa_2CO_3[/tex]
Explanation:
Hello,
In this case, by considering the given seminormal solution, we infer it is a 0.5-N solution which means that we can obtain the equivalent grams as shown below for the 55 cc (0.055 L) volume:
[tex]eq-g=0.5eq-g/L*0.050L=0.025eq-g[/tex]
Next, since sodium carbonate has two sodium ions with a +1 oxidation state each, we can obtain the moles:
[tex]mol=0.025eq-gNa_2CO_3*\frac{1molNa_2CO_3}{2eq-gNa_2CO_3}\\ \\mol=0.0125molNa_2CO_3[/tex]
Finally, the mass is computed by using its molar mass (106 g/mol)
[tex]m=0.0125molNa_2CO_3*\frac{106gNa_2CO_3}{1molNa_2CO_3} \\\\m=1.325gNa_2CO_3[/tex]
Regards.
The density of mercury is 13.6 g/mL what is the density in lbs/L ( 1 lb hint =0.454 kg )
Answer:
[tex]30.0\frac{lb}{L}[/tex]
Explanation:
Hello,
In this case, since 454 g are equivalent to 1 pound and 1000 millilitres are equivalent to 1 liter, the required density is computed below by applying the corresponding conversion factor:
[tex]=13.6\frac{g}{mL} *\frac{1lb}{454g} *\frac{1000mL}{1L} \\\\=30.0\frac{lb}{L}[/tex]
Regards.
Water flows over Niagara Falss at the average rate of 2,400,000 kg/s, and the average height of the falls is about 50 m. Knowing that the graviatational potential energy of falling water per second = mass (kg) x height (m) x gravity (9.8 m/s2), what is the power of Niagara Falls? How many 15 W LED light bulbs could it power?
Answer:
1. 176 × 10^12 W ; 78400000000
Explanation:
Given the following :
Fall rate = 2,400,000kg/s
Average height of fall = 50m
Gravitational Potential of falling water = mgh = mass × acceleration due to gravity × height =
How many 15 W LED light bulbs could it power?
Recall : power = workdone / time
Workdone = gravitational potential energy
Mass of water = density * volume
Density of water = 1 * 10^3kg/m^3
Rate of fow = volume / time = 2400000
Hence,
Power = 1000 * 2,400,000 * 9.8 * 50
Power = 1176000000000
Power = 1. 176 × 10^12 W
How many 15 W LED light bulbs could it power?
1176000000000 / 15 = 78400000000
= 78400000000 15 W bulbs
Help! It’s for chemistry I attached a picture thank you!
Answer:
0.15 L
Explanation:
You need to first find the volume of the container. You can do this by dividing the mass by the density. This will give you the mass in mL.
5.00 kg = 5,000 g
(5,000 g)/(1.00 g/mL) = 5,000 mL
5,000 mL = 5 L
Now, find the volume the seawater will take up.
(5,000 g)(1.03 g/mL) = 4854.4 mL
4854.4 mL = 4.85 L
Subtract the two volumes to find the volume that left unfilled.
5 L - 4.85 L = 0.15 L
Considering the redox reaction Cr + Ni²⁺ → Cr³⁺ + Ni, how many electrons are transferred in the balanced reaction?
Answer:
The correct answer is : 6 electrons
Explanation:
From the reduction-oxidation reaction, we identify the half-reactions:
Oxidation reaction: Cr (oxidation number= 0) loses 3 electrons and forms the cation Cr³⁺.
Cr → Cr³⁺ + 3 e-
Reduction reaction: the cation Ni²⁺ gains 2 electrons to form Ni (oxidation number= 0).
Ni²⁺ + 2 e- → Ni
We write the two half-reactions together and we multiply the reduction reaction by 3 and the oxidation reaction by 2 to obtain the same quantity of electrons in each half-reaction: 6.
(Ni²⁺ + 2 e- → Ni) x 3
(Cr → Cr³⁺ + 3 e-) x 2
-------------------------------
3 Ni²⁺ + 2 Cr → 3 Ni + 2 Cr³⁺ (balanced reaction)
Therefore, in the balanced reaction a total of 6 electrons are transferred.
3.25 kcal is the same amount of energy as
Answer:
3.25 kcal has the same amount of energy as 13600 J
What is the concentration of OH− and pOH in a 0.00072 M solution of Ba(OH)2 at 25 ∘C? Assume complete dissociation.
Given :
0.00072 M solution of [tex]Ba(OH)_2[/tex] at [tex]25^oC[/tex] .
To Find :
The concentration of [tex]OH^-[/tex]and pOH .
Solution :
1 mole of [tex]Ba(OH)_2[/tex] gives 2 moles of [tex]OH^-[/tex] ions .
So , 0.00072 M mole of [tex]Ba(OH)_2[/tex] gives :
[tex][OH^-]=2 \times 0.00072\ M[/tex]
[tex][OH^-]=0.00144\ M[/tex]
[tex][OH^-]=1.44\times 10^{-3}\ M[/tex]
Now , pOH is given by :
[tex]pOH=-log[OH^-]\\\\pOH=-log[1.44\times 10^{-3}]\\\\pOH=2.84[/tex]
Hence , this is the required solution .
The element rubidium forms a _______ with the charge . The symbol for this ion is , and the name is . The number of electrons in this ion is .
Answer:
The element rubidium forms a cation with a charge of +1. The symbol of this ion is Rb+, and the name is rubidium ion. The number of electrons in this ion is 36 electrons
Explanation:
Rubidium belongs to the group 1A of the periodic table of elements. It is an alkali metal. The rubidium atom has an atomic number of 37. The neutral atom also has 37 electrons.
Being a metal, it forms ions by the loss of electrons. Since it is an alkali metal, it has one valence shell electron. It loses this one electron to form the rubidium ion, Rb+ which then has 36 electrons.
The sum of gravitational potential energy and kinetic
energy is called mechanical energy. Use Figure 2 to find the mechanical energy
of an idealized pendulum at a variety of times in its cycle. Identify any pattern you
notice in the values of mechanical energy.
Answer:
Explanation:
Mechanical energy = Gravitational potential energy + kinetic energy
Time Gravitational potential energy kinetic energy Total ME
0 4 0 4
2 2 2 4
4 0 4 4
6 2 2 4
8 4 0 4
and so on .....
We see that total mechanical energy is always 4 which is constant .
So gravitational and kinetic energy changes cyclically but total mechanical energy is constant .
which variable is directly proportional to frequency?
velocity
wavelength
position
energy
Answer:
its letter D Energy I think
What is the density of an object with a volume of 30ml and a mass of 90 grams
Answer:
Density = 3 g/mLExplanation:
Density of a substance can be found by using the formula
[tex]Density = \frac{mass}{volume} [/tex]From the question
mass = 90 g
volume = 30 mL
Substitute the values into the above formula and solve for the Density
That's
[tex]Density = \frac{90}{30} \\ = \frac{9}{3} [/tex]We have the final answer as
Density = 3 g/mLHope this helps you
PLEASE HELP I WILL GIVE BRAINLIEST 40+ POINTS. PLEASE
This is the periodic table(image below)
Using information from the periodic table, which diagram shows a
correct model for an atom neon(also image below)
Answer:
A.
Explanation:
Neon 19 is shown on image A.
Diagram A shows the correct model for an atom neon.
What are the properties of periodic table ?The arrangement of elements by their periodic properties and physical and chemical characteristic make a periodic table.
The chemical and physical properties of the group of the element belongs to Alkali Metals, Less dense, One loosely bound valence electron, Highly reactive, Low ionization energy, Low electronegativity
The lanthanides and actinides are also transition metals, these are softer and nonmetallic properties, all of these elements tend to have a shiny, metallic appearance, radioisotopes of other elements, actinides are radioactive.
Learn more about periodic table, here:
https://brainly.com/question/11155928
#SPJ2
150.0 grams of an isotope with a half-life of 36.0 hours is present at time zero. How long will it take
to decay to 18.75g?
Given :
Initial mass , a = 150 gm .
Half time ,
[tex]t_{\dfrac{1}{2}}=36 \ hours[/tex].
Final mass , x = 18.75 gm .
To Find :
The time taken to decay 18.75 gm .
Solution :
We know , time taken is given by :
[tex]t=\dfrac{1}{k}\times ln(\dfrac{a}{a-x})[/tex]
Here , k is a constant given by :
[tex]k=\dfrac{0.693}{t_{\dfrac{1}{2}}}\\\\\\k=\dfrac{0.693}{36}[/tex]
Putting all given value in above equation :
We get :
[tex]t=\dfrac{36}{0.693}\times ln(\dfrac{150}{150-18.75})\\\\t=6.94\ hours[/tex]
Therefore , time taken is 6.94 hours .
Hence , this is the required solution .
interpretacao gerais das praticas
sobre densidade de amostra solido e liquido
Answer:
O sólido tem densidade mais alta em comparação ao líquido.
Explicação:
A densidade da amostra sólida é maior do que a densidade do líquido porque há pouco espaço entre as partículas do sólido. A densidade tem relação inversa com o volume de uma substância, se uma substância ocupa mais espaço então sua densidade é menor, enquanto se a substância ocupa menos espaço então tem maior densidade. As substâncias sólidas ocupam menos espaço em comparação com as substâncias líquidas, então podemos dizer que a densidade do sólido é maior do que as substâncias líquidas.
SpongeBob & Friends and the Scientific Method
Scenario A. Krusty Krabs Breath Mints
Mr. Krabs created a secret ingredient for a breath mint that he thinks will "cure the bad breath people get from
cating crabby patties at the Krusty Krab. He asked 100 customers with a history of bad breath to try his new
breath mint. He had fifty customers (Group A) cat a breath mint after they finished eating a crabby patty. The
other fifty (Group B) also received a breath mint after they finished the sandwich, however, it was just a regular
breath mint and did not have the secret ingredient. Both groups were told that they were getting the breath mint
that would cure their bad breath. Two hours after cating the crabby patties, thirty customers in Group A and ten
customers in Group B reported having better breath than they normally had after cating crabby patties.
1. Which people are in the control group?
2. What is the independent variable?
3. What is the dependent variable?
4. What should Mr. Krabs' conclusion be?
5. Was this a quantitative or a qualitative measurement?
6. Why do you think 10 people in group B reported fresher breath?
Answer:
1. Which people are in the control group? The people who received the mint without the secret ingredient
(Group B) would be the control group.
2. What is the independent variable? Secret ingredient in the breath mint
3. What is the dependent variable? Amount of breath odor (or bad breath)
4. What should Mr. Krabs’ conclusion be? The breath mint with the secret ingredient appears to reduce the
amount of breath odor more than half the time, but it is not 100% effective.
5. Why do you think 10 people in group B reported fresher breath? This may be due to the placebo effect.
g A sample of unknown gas has a mass of 1.95 g and occupies 3.00 L at 1.25 atm and 20 C. What is the molar mass of the unknown gas
Answer:
Molar mass = 12.51 g/mol
Explanation:
V = 3L
P = 1.25 atm
T = 20 C = 20 + 273 = 293 K (Upon conversion to kelvin temperature)
n =?
m = 1.95g
Molar mass = ?
The variables are related by the follwing equation;
pV = nRT
where r = gas constant = 0.0821 L atm K−1
Solving for n, we have;
n = pV / RT
n = (1.25 * 3 ) / (0.0821 * 293)
n = 3.75 / 24.0553 = 0.1559 mol
The relationship between number of moles, n and molar mass is given as;
n = mass / molar mass
Molar mass = Mass / n = 1.95 / 0.1559
Molar mass = 12.51 g/mol
If 5.0 kJ of energy is added to a 15.5-g sample of water at 10.°C, the water is Group of answer choices
Answer:
The water is completely vaporized at this stage.
Explanation:
The complete question is
If 5.0 kJ of energy is added to a 15.5-g sample of water at 10.°C, the water is
-boiling
-completely vaporized
-frozen solid
-decomposed
-still a liquid
Energy added = 50 kJ = 50000 J
mass of water = 15.5 g = 0.0155 kg
temperature of water = 10 °C
We know that the energy posses by a mass of water at a given temperature is given as
H = mcT
where H is the energy possessed by the mass of water
m is the mass of the water
c is the specific heat capacity of water = 4200 J/ kg- °C
T is the temperature of the water
substituting values, the energy of this amount of water is
H = 0.0155 x 4200 x 10 = 651 J
If 50 kJ is added to the water, the energy increases to
50000 J + 651 J = 50651 J
Temperature of this water at this stage will be gotten from
H = mcT
we solve for the new temperature
50651 = 0.0155 x 4200 x T
50651 = 65.1 x T
T = 50651/65.1 = 778.05 °C
This temperature is well over 100 °C, which is the vaporization temperature of water, but less than 3000 °C for its molecules to decompose.
What is all matter I’m the universe made of?
Answer:
The building block that makes up all matter in the universe is atoms.
Draw the neutral organic product expected under these reaction conditions.
Answer:
The neutral organic product is Imine.
Explanation:
From the image attached below, we will see an organic compound the question intended us to work out.
The proposed reaction is between cyclohexane and a stick structure of butylamine to yield imine as the product. The stepwise process and the mechanism carried out to get the product of this reaction is also shown in the image attached below.
A student uses paper towels to clean up a small chemical spill in the lab.
Where should the dirty paper towels be placed?
A in the lab sink
B in the wastebasket
C in the chemical waste container
D in the hazardous waste container
Answer:
C. in the chemical wastebasket
Will a deflated football sink in water?
Answer:
no
Explanation:
light objects float
At what atom of the pyridine ring will oxidation and reduction reactions take place?a. 2.b. 4.c. 3.d. 1.
Answer:
1
Explanation:
Pyridine is a six membered hetrocyclic aromatic compound. Oxidation of the pyridine ring occurs at position-1.
Just like benzene, pyridine is stable towards mild oxidizing agents, however, pyridine is oxidized by peracetic acid to yield pyridine N-oxide.