Answer:
measurements are important to do calculations to get correct results and without them scientists cannot form theories
What are the standard temperature and pressure conditions enthalpy is usually measured under
Answer:
temperature must be 273 Kelvin (0°C)
pressure must be 1 atm
Hạt nhân nguyên tử được tạo bởi
Answer:
The FitnessGram™ Pacer Test is a multistage aerobic capacity test that progressively gets more difficult as it continues. The 20 meter pacer test will begin in 30 seconds. Line up at the start. The running speed starts slowly, but gets faster each minute after you hear this signal. [beep] A single lap should be completed each time you hear this sound. [ding] Remember to run in a straight line, and run as long as possible. The second time you fail to complete a lap before the sound, your test is over.
The boiling points of diatomic halogens are compared in the table.
Boiling Points of Diatomic
Halogens
Molecule
Boiling Point
F2
-188 °C
Cl2
-34 °C
Br2
59 °C
12
184°C
Which of the following statements best explains the trends in boiling points?
The atomic size increases down the group, and this decreases the strength of the intermolecular forces.
The total number of electrons decreases down the group, and this decreases the strength of the intermolecular forces.
The total number of electrons increases down the group, and this increases the strength of the intermolecular forces.
The chances of forming a permanent dipole increases down the group, and this increases the strength of the intermolecular forces.
Which of the following statements best explains the trends in boiling points?
A. The atomic size increases down the group, and this decreases the strength of the intermolecular forces.
A is incorrect
B. The total number of electrons decreases down the group, and this decreases the strength of the intermolecular forces.
B is incorrect
C. The total number of electrons increases down the group, and this increases the strength of the intermolecular forces.
C is correct
D. The chances of forming a permanent dipole increases down the group, and this increases the strength of the intermolecular forces.
D is incorrect
The boiling point increase down a group because the total number of electrons increases down the group, and this increases the strength of the intermolecular forces. Hence option C is correct.
What is boiling point?Boiling point of a substance is the temperature at which the substance changes from its liquid state to vapour state. Boiling point of a molecule or compounds depends on the bond type, molecular weight, temperature and pressure.
For ionic compounds, boiling point will be higher since ionic bonds are stronger than covalent compounds. There is a periodic trend for the physical properties such as boiling point for elements in periodic table.
Down a group, the number of electrons increases and the atomic size also as well as the ionic character increases down a group . These two facts leads to higher intermolecular attraction, thus more temperature have to applied to weaken the bonds.
Higher temperature to be applied means the boiling point of the substance is higher. Therefore, boiling point down a group increases because of the higher intermolecular attraction as said in option C.
To find more about boiling point, refer the link below:
https://brainly.com/question/2153588
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How does the useable atoms of elements attain stability? Illustrate your answer with two example.
Answer:
An element which does not have two or eight electrons in its valence shell is unstable. It get stability by losing, gaining or sharing electron to complete noble gas electronic configuration. ... Elements attain stability by completing duplet or octet.
Which factor would speed up a chemical reaction? (Choose all that apply)
Decreasing particle size
Increasing the temperature
Decreasing the temperature
Increasing particle size
Answer:
Increasing the temperature
Increasing particle size
Explanation:
Increasing the temperature allows for particles and molecules to move faster (because there is an increase in energy) and allows for more collisions.
∴ Increasing the temperature would be an answer.
Increasing the particle size allows for more surface area and a greater chance for particles to collide with each other.
∴ Increasing particle size would be an answer.
Topic: AP Chemistry
Unit: Kinetics
You mix the sample discussed in the previous two questions with another sample, which you know to be pure acetylsalicylic acid. You grind the mixture thoroughly with a mortar and pestle, and do a melting point determination on the mixed product. You now observe melting over a range of 127 to 133 C. Now what conclusions can you reach regarding the original product
Answer:
Having high melting point.
Explanation:
The original product has high melting point as compared to the mixture product because in the original product, the element is present in its pure state and we know that pure substances have high melting point as compared to mixture substances due to the presence of strong intercellular forces between them which is hard to break so that's why we can say that the original product has high melting point.
what is used in conjunction with a scale balance to weigh dry chemicals
Can someone tell me the advantages and disadvantages of Ceramics? I need scientific, good and clear points! :)
ASAP
The concentration of reactants and products and the rate of reaction were measured during a chemical reaction. After the first 3 seconds, the rate of reaction was 1.8 x10−6 M/s. Which of the following would explain a lower rate after another 3 seconds?
A - The concentration of reactants increased while the concentration of product decreased.
B - The concentration of reactants decreased while the concentration of product increased.
C - All concentrations of reactants and products decreased.
D - All concentrations of reactants and products increased.
Answer:
B
Explanation:
During the first half of the reaction there was an increase in the rate of reaction due to the high concentration of the reactants. But as the reaction continues we witness a decrease in the amount of reactants which lowers the rate.
Answer:
B. The concentration of reactants decreased while the concentration of product increased.
Explanation:
took the test :)
Can someone help me with this please
Answer:
.00305
Explanation:
There a 7 significant figures in the number because we know that leading zeroes are NOT counted. To round the number to have only 3 significant figures, we will need to round to the 5th decimal place. Remember the basic rules of rounding; 5 and up, round up, 4 and below, round down.
.00305346 → .00305
Best of Luck!
3. A typical peanut butter and jelly sandwich contains 360 kcal, of which 160
kcal comes from fat. Given 1 kcal = 4.2 kJ, how many J of fat would there be
in one PB&J sandwich?
Explanation:
here's the answer to your question
Prepare a project report on various samples of a) a mixture b) a compound c) an element (metal or nonmetal)
Answer:
Any substance that contains only one kind of an atom is known as an element. Because atoms cannot be created or destroyed in a chemical reaction, elements such as phosphorus (P4) or sulfur (S8) cannot be broken down into simpler substances by these reactions.
Example: Water decomposes into a mixture of hydrogen and oxygen when an electric current is passed through the liquid. Hydrogen and oxygen, on the other hand, cannot be decomposed into simpler substances. They are therefore the elementary, or simplest, chemical substances - elements.
Each element is represented by a unique symbol. The notation for each element can be found on the periodic table of elements.
The elements can be divided into three categories that have characteristic properties: metals, nonmetals, and semimetals. Most elements are metals, which are found on the left and toward the bottom of the periodic table. A handful of nonmetals are clustered in the upper right corner of the periodic table. The semimetals can be found along the dividing line between the metals and the nonmetals.
Explanation:
Determine the empirical formula for compounds that have the following analyses. a. 28.4% copper, 71.6% bromine b. 39.0% potassium, 12.0% carbon, 1.01% hydrogen, and 47.9% oxygen c. 77.3% silver, 7.4% phosphorus, 15.3% oxygen d. 0.57% hydrogen, 72.1% iodine, 27.3% oxygen
Answer:
See explanation
Explanation:
Cu- 28.4/63.5, Br- 71.6/80
Cu- 0.447/0.447, Br- 0.895/0.447
Cu- 1, Br - 2
Empirical formula = CuBr2
b)
K- 39.0/39, C-12.0/12, H- 1.01/1, O- 47.9/16
K= 1, C-1, H- 1. O-3
Empirical formula= KHCO3
c)
Ag- 77.3/108, P-7.4/31, O-15.3/16
Ag-0.716/0.239, P- 0.239/0.239, O-0.956/0.239
Ag-3, P-1, O-4
Empirical formula= Ag3PO4
d)
H-0.57/1, I- 72.1/127, O-27.3/16
H- 0.57/0.57, I- 0.57/0.57, O-1.71/0.57
H-1, I-1, O- 3
Empirical formula= HIO3
Urgent please help
A.Ca
B. CaO
C.CO
In the reaction at Blood Falls, iron and oxygen combine to form iron oxide, which is called rust (water is also present). The reactants are
, and the product is
Answer:
The reactants for rust are iron ,water and oxygen while the products are hydrated iron oxide
Explanation:
4Fe+3O2+2H2O---->2Fe2O3.H2O
How many moles of oxygen are required to react completely with 5 mol C8H18?
Answer:
62.5 moles of O₂.
Explanation:
We'll begin by writing the balanced equation for the reaction. This is illustrated below:
2C₈H₁₈ + 25O₂ —> 16CO₂ + 18H₂O
From the balanced equation above,
2 moles of C₈H₁₈ reacted with 25 moles of O₂.
Finally, we shall determine the number of mole of O₂ needed to react with 5 moles of C₈H₁₈. This can be obtained as shown below:
From the balanced equation above,
2 moles of C₈H₁₈ reacted with 25 moles of O₂.
Therefore, 5 moles of C₈H₁₈ will react with = (5 × 25) / 2 = 62.5 moles of O₂.
Thus, 62.5 moles of O₂ is needed for the reaction.
Which of the following elements would you expect to be most reactive, based
on the number of valence electrons it has?
Answer:
C. Lithium
Explanation:
This image describes the trend in reactivity. Group 1 metals are always the most reactive so yeah :)
the element of group 1 hour reactive but those of group 18 are inert, why?
Answer:
The noble gases (Group 18) are located in the far right of the periodic table and were previously referred to as the "inert gases" due to the fact that their filled valence shells (octets) make them extremely nonreactive.
An aqueous solution contains
32.7% KCl (weight/weight %).
How many grams of water (H20) are contained in 100 g of this solution?
Answer:
67.3g
Explanation:
%(w/w) = mass of solute/total mass of solution × 100
According to this question, an aqueous solution contains 32.7% KCl (w/w%). Firstly, we find the mass of the solute (KCl) as follows, if the mass of solution is 100g:
32.7 = mass of solute/100 × 100
mass of solute (KCl) = 32.7g
Mass of solution = mass of solvent (water) + mass of solute (KCl)
100g = x + 32.7g
x = 100 - 32.7
x = 67.3
Hence, the mass of water contained in the 100g solution is 67.3g.
name some examples of chemical solutions and maybe give a clear explanation as to what chemical solutions are
Answer:
Some examples of solutions are salt water, rubbing alcohol, and sugar dissolved in water. ... In our example of salt water, the solute is the salt. Solvent: this is the substance that makes up the majority of the solution. This is the part where the solute is dissolved.
Explanation:
I hope they should be right answer
balance chemical reaction of oxalic acid with conc. sulphuric acid
Answer:
Explanation: since oxalic acid is a weak acid it wont provide a strong acidic medium. So in order to provide a strong acidic medium dilute sulphuric acid is added.
CaCO3 + 2HCl > CaCl2 + CO₂ + H₂O
Explanation:
This reaction is also known as double decomposition reaction.
HCl + CaCO3 + MgCO3 → H2O + H2 + CO2 + CaCl2 + MgCl2
please help me with this question.
ps: kindly include a drawing.
Answer:
gallium has orthorhombic and forms ionic bonds with metals
Explanation:
(Q008) Two physical properties of minerals both result in smooth, flat surfaces with specific angles between them. The first property is externally visible and is the result of how the mineral forms; the second is inherently internal and is the result of breaking a sample of the mineral. These properties are called
Answer: Crystal habit and cleavage.
Explanation:
When two physical properties of minerals both bring about smooth, flat surfaces that has specific angles between them.such that the first property is externally visible and is the result of how the mineral forms while the second property is internal and is the result of breaking a sample of the mineral, it should be noted that the properties are refered to as the crystal habit and cleavage.
It should be noted that the cleavage refers to the tendency of crystalline materials to be able to split along the structural planes.
A block of dry ice (-40°C) is placed in contact with an ice cube (-10°C).
What will happen, assuming no chemical reactions occur?
O Heat will flow from the ice cube to the dry ice.
O Heat will flow from the dry ice to the ice cube.
O There is no way to tell without a thermometer
O No heat will flow.
Explanation:
Answer is that : no heat will flow
Answer:
Heat will flow from the ice cube to the dry ice
Explanation:
is magnetism, reactivity, and fluorescence used to identify minerals
which state of matter expands most when heated
Answer:
Gases expand the most upon heating because the intermolecular space is more than in solids or liquids.
Explanation:
hopes it helps
hii pls help me to balance the equation thanksss
Answer:
2H2S (g) + 3O2 (g) = 2H2O (l) + 2SO2 (g)
▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓
[tex]\boxed{\pmb{\green{\sf{2H_{2}S(g) + 3O_{2}(g)\dashrightarrow 2H _{2}O(l)+2SO_{2}(g)}}}}[/tex]
▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓
Plz help I will give brainliest
Answer:
1. Fr
2. cl
3.H20
4.2 mole
5. 3
6. c
what is true about solubility
Explanation:
Solubility is defined as a property of solutes by virtue of which they get dissolved in a favorable solvent. The solute can only be dissolved in any suitable solvent up to a limit at a given temperature. This is a characteristic of the the solute-solvent pairing.
