Answer:
A. 0°C............... sorry, the anwser has to be 20 characters long
can i do chemistry project on effects of caffeine
Answer:
You do as you wish, but it isn't a terrible idea.
Explanation:
Caffeine is a drug that has been normalized in society for a long time. But it's effects on the nervous, digestive, excretory, and circulatory systems are a good basis to start a project off of.
Cheers! (:
Number of molecules in 16 grams of h2co3
For this one u can work out the amount of moles in h2co3 by using moles=mass/mr(of h2co3 is 52)
so 16/62=0.258moles then u use the equation
number of particle = moles × 6.02×10^23
=0.258×6.02 ×10^23
=1.55×10^23 molecules.
hope this helps
What is the mass of 0.251 moles of water? Using dimensional analysis show work
[tex]1 \text{ mol of H}_2 \text{O} \equiv 18 \text{ g} \implies 0.251 \text{ moles of H}_2 \text{O} \equiv 4.518 \text{ g}[/tex]
In lab, you calculate the density of an iron rod to be 7.30 g/cm3. The accepted value
for the density of iron is 7.80 g/cm3. What is your percent error?
Answer:
6.41 %Explanation:
The percentage error of a certain measurement can be found by using the formula
[tex]P(\%) = \frac{error}{actual \: \: number} \times 100\% \\ [/tex]
From the question
actual density = 7.80 g/cm³
error = 7.30 - 7.80 = 0.5
We have
[tex]p(\%) = \frac{0.5}{7.8} \times 100 \\ = 6.410256...[/tex]
We have the final answer as
6.41 %Hope this helps you
125 cm3 of a solution contains 0.25 moles of the solute. What is the concentration of the solution?
Answer:
Explanation:
125 cm3 -> 0.125 L
M = no. mole / volume (L)
M = 0.25 / 0.125 = 2 M
The solubility of gases in liquids The solubility of gases in liquids increases as temperature increases and increases as pressure increases. increases as temperature increases and decreases as pressure increases. decreases as temperature increases and decreases as pressure increases. decreases as temperature increases and increases as pressure increases. is independent of temperature and increases as pressure increases.
Answer:
As the kinetic energy of the gaseous solute increases, its molecules have a greater tendency to escape the attraction of the solvent molecules and return to the gas phase. Therefore, the solubility of a gas decreases as the temperature increases.
Explanation:
As the kinetic energy of the gaseous solute increases, its molecules have a greater tendency to escape the attraction of the solvent molecules and return to the gas phase. Therefore, the solubility of a gas decreases as the temperature increases
What makes up a compound
Answer:
Elements make up a compound.
Which electron in an atom (Z=17) is the most shielded from
nuclear charge?
A. an electron in the 2s
B. an electron in the 3p
C. an electron in the 3d
D. an electron in the 1s
Answer:
option no. C is correct
an electron in the 3d
Please help .. I’m really stuck
Answer:
See explanation
Explanation:
pOH = -log[OH^-]
pOH =-log[1×10^-4 molL-1]
pOH = 4
pH +pOH =14
pH = 14 -4
pH =11
b) pOH = -log[OH^-]
pOH =-log[4.9×10^-2molL-1]
pOH = 1.31
pH +pOH =14
pH = 14 -1.31
pH =12.69
c)
pH= -log[H^+]
[H^+] = Antilog [-pH]
[H^+] = Antilog [-3]
[H^+] = 1 × 10^-3 molL-1
d) pOH = -log[OH^-]
[OH^-] = Antilog[-pOH]
[OH^-] = Antilog[-10.4]
[OH^-] = 3.98 ×10^-11
[OH^-] [H^+] = 1 × 10^-14
[H^+] = 1 × 10^-14/3.98 ×10^-11
[H^+] =2.5 ×10^-4 MolL^-1
e) A solution of pH 9 is basic because the pH scale is calibrated in such as way that 0-6.9 is acidic, 7 is neutral and 8 - 14 is basic.
f)
[H^+] = number of moles/volume
[H^+] = 0.35 moles/8L
[H^+] = 0.044 MolL^-1
pH = - log [H^+]
pH = -log [0.044 MolL^-1]
pH= 1.36
The atoms of which element bond to one another in chains, rings, and networks?
1.
barium
2.
carbon
3.
iodine
4.
mercury
Submit An:
A curium-245 nucleus is hit with a neutron and changes as shown by the equation. Complete the equation by filling in the missing parts. 52 54 138 140 142 Xe Te Ce
The question is incomplete, the complete question is:
A curium-245 nucleus is hit with a neutron and changes as shown by the equation. Complete the equation by filling in the missing parts.
[tex]_{96}^{245}\textrm{Cm}+_0^1\textrm{n}\rightarrow _{42}^{103}\textrm{Mo}+_{r}^{q}\textrm{p}+3_0^1\textrm{n}[/tex]
Answer: The complete equation formed is [tex]_{96}^{245}\textrm{Cm}+_0^1\textrm{n}\rightarrow _{42}^{103}\textrm{Mo}+_{54}^{140}\textrm{Xe}+3_0^1\textrm{n}[/tex]
Explanation:
The general representation of an isotope is given as:
[rex]_Z^A\textrm{X}[/tex]
where,
A is the mass number, Z is the atomic number and X is the symbol of the element
In a nuclear reaction, total atomic number and total mass number on either side of the reaction remains the same
For the given chemical reaction:
[tex]_{96}^{245}\textrm{Cm}+_0^1\textrm{n}\rightarrow _{42}^{103}\textrm{Mo}+_{r}^{q}\textrm{p}+3_0^1\textrm{n}[/tex]
On the reactant side:
Total atomic number = [96 + 0] = 96
Total mass number = [245 + 1] = 246
On the product side:
Total atomic number = [42 + r + 0] = 42 + r
Total mass number = [103 + q + 3] = 106 + q
Calculating for 'r' and 'q', we get:
[tex]96= 42 + r\\\\r=96-42=54[/tex]
[tex]246 = 106+q\\\\q=246-106=140[/tex]
Thus, the missing isotope is [tex]_{54}^{140}\textrm{Xe}[/tex]
Hence, the complete equation formed is [tex]_{96}^{245}\textrm{Cm}+_0^1\textrm{n}\rightarrow _{42}^{103}\textrm{Mo}+_{54}^{140}\textrm{Xe}+3_0^1\textrm{n}[/tex]
Answer: try 140 52 xe
Explanation:
A population of Esherichia coli is given time to grow for eight generations. The final population is 1,996,800 cells. What was the initial population in cells?
Answer:
7800 cells
Explanation:
The number of Escherichia coli cells N after n generations is given by
N = 2ⁿ × N₀ where N₀ = initial population
Now making N₀ subject of the formula, we have
N₀ = N/2ⁿ
Since n = 8 and N = 1,996,800 cells, substituting the values of the variables into the equation, we have
N₀ = N/2ⁿ
N₀ = 1,996,800 cells/2⁸
N₀ = 1,996,800 cells/256
N₀ = 7800 cells
So, the initial population of Escherichia coli cells is 7800 cells.
help bc i need it lol
Answer:
2 XE + 1 AB. --> 1 AE2 + 2 XB
Above equation is now balanced
Which of the following most likely happens when the number of particles of a gas decreases?
The pressure of the gas increases.
The pressure of the gas remains same.
The number of collisions of gas particles decreases.
The number of collisions of gas particles remains same.
Answer: C. The number of collisions of gas particles decreases
Explanation: As temperature decreases so does everything else same with increase.
When the number of particles of a gas decreases the pressure of the gas increases.
Factors affecting has pressureIn a container containing has molecules, they move about freely in the container but the pressure it exerts on its container depends increase of decrease of the has molecules by volume.
If the volume of a container is decreased, the gas molecules have less space in which to move around. As a result, they will strike the walls of the container more often and the pressure increases.
Therefore, when the number of particles of a gas decreases the pressure of the gas increases.
Learn more about gases here:
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The molar mass of copper(II) chloride (CuCl2) is 134.45 g/mol. How many formula units of CuCl2 are present in 17.6 g of CuCl2?
Answer:
7
Explanation:
took test
Please help! I don't know how to do and want to understand
What has the most direct cause to the increase in the number and ferocity (strength) of storms hitting the Caribbean and the United States in recent years?
Answer:
High amount of humidity
Explanation:
This is especially common in the Caribbean, where hot temperatures very moisture and warm air provide near-ideal circumstances for hurricane formation, as assessed by the Saffir-Simpson classification and the Power Distribution Index.
"Hurricanes may originate everywhere in the Atlantic basin, from the subtropical central Atlantic to the Gulf coast. However, in order to make this all the way to the West Coast of the United States, the storms must pass over a lengthy length of sea water which is far too small to support hurricanes.
The storm strength is influenced by a lot of factors. Due to world warms and increase in the amount of humidity.
What is causing the increase in storm strength?
Studies has shown due too the warming of the world, hurricanes and other tropical cyclones are said to be more stronger.
This is due to the fact that warmer water gives more of the energy that boast storms. A rise in stronger hurricanes is due to warming never ending.
Learn more about storm strength from
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A certain atom has a mass of 16 and an atomic number of 7. What element is this ?
Answer:
Nitrogen
Explanation:
According to the Periodic Table, the atom with a mass is 16 but the Atomic number is 7 for Nitrogen. That means that Nitrogen is an isotope.
The diagram shows the basis for forming which of the following?
O nucleic acids
O proteins
O polysaccharides
O lipids
NEED HELP ASAP PLEASE
Identify the type of bonding, covalent, ionic, or metallic, between
the atoms in an oxygen molecule.
Answer:
here hope it helps
Explanation:
covalent bonds
Which of these takes place when a chemical change occurs? option 1: Bonds connecting atoms in products and reactants form. option 2: Bonds connecting atoms in products and reactants break. option 3: Bonds connecting atoms in reactants break, and bonds connecting atoms in products form. option 4: Bonds connecting atoms in reactants form, and bonds connecting atoms in products break.
Answer: Out of the given options bonds connecting atoms in reactants break, and bonds connecting atoms in products form are the changes which takes place when a chemical change occurs.
Explanation:
A change that leads to the change in chemical composition of a substance is called a chemical change.
For example, [tex]2NH_{3} \rightarrow N_{2} + 3H_{2}[/tex]
Here, bond between the reactant atoms nitrogen and hydrogen is broken down.
On the other hand, bond connecting the products that is [tex]N_{2}[/tex] and [tex]H_{2}[/tex] is formed.
Thus,, we can conclude that out of the given options bonds connecting atoms in reactants break, and bonds connecting atoms in products form are the changes which takes place when a chemical change occurs.
Aluminum reacts with oxygen to form aluminum oxide. Select the correct unbalanced skeleton equation for this reaction. A. Al(s) + 0(g) - AIO(s) B. Al203(s) - Al(s) + 02(8) C. Al(s) - 02(8) + Al203(s) D. Al(s) + 02(8) - Al203(s)
Answer:
D. Al(s) + O₂(g) → Al₂O₃(s)
Explanation:
Aluminum is a solid metal, so it is written as Al(s).
Oxygen is a diatomic gas, so we write this compound as O₂(g).
Aluminum oxide has the formula Al₂O₃ because in oxides the oxidation number of oxygen atom is -2 and for aluminum, the oxidation number is 3. Thus, we write this compound as Al₂O₃(s).
Now, we have to found the chemical equation in which the reactants (left side) are Al(s) and O₂(g) while the product (right side) is Al₂O₃(s). From the options, we can see that the correct is (D):
Al(s) + O₂(g) → Al₂O₃(s)
What is the SI unit of mass
Answer:
kg or kilograms
Explanation:
Answer: Kilogram (kg)
Explanation: The SI unit of mass is the kilogram (kg). It is equal to the mass of the international prototype of the kilogram and it is defined as the mass of platinum-iridum (Pt-Ir).
In the titration of a solution of Sodium hydroxide, an acid titrant was prepared by diluting 125.0 mL of 10.00 mol/L Nitric acid into enough distilled water to make 500.0 mL of solution. 30.0 mL of the base was measured, and in the titration, 16.74 mL of the acid titrant was needed to neutralize. Determine the concentration of the Sodium hydroxide.
Answer:
1.395M NaOH
Explanation:
Sodium hydroxide, NaOH, reacts with nitric acid, HNO3, as follows:
NaOH + HNO3 → NaNO3 + H2O
Where 1mol of NaOH reacts with 1mol of HNO3
To solve this question we must find the concentration of the titrant. With the concentration and the needed acid we can find the moles of HNO3 added = moles NaOH in the solution. With the moles of NaOH and its volume we can find its concentration as follows:
HNO3 concentration:
10.00mol/L HNO3 * (125.0mL/500.0mL) = 2.500M HNO3
Moles HNO3 = Moles NaOH:
16.74mL = 0.01674L*(2.500mol/L) = 0.04185 moles HNO3 = Moles NaOH
Concentration NaOH:
0.04185 moles / 0.0300L =
1.395M NaOH
In its aqueous solution, 32% of a substance dissociates to release hydroxide ions. Which of the following is true for the substance? (3 points)
It is a weak acid
It is a weak base.
It is a strong acid
It is a strong base.
*please only answer is you have the real answer bc I really need to bring up my grade*
Answer:
It is a weak base.
Explanation:
A base is a substance that releases hydroxide ion (OH-) when in an aqueous solution, according to Svante Arrhenius definition of a base. However, a base is said to be either strong or weak depending on it is able to dissociate.
A weak base is a base that does not completely dissociate into hydroxide ions in an aqueous solution while a strong base dissociates completely. According to this question, 32% of a basic substance ( because it can dissociate into OH-) dissociates to release hydroxide ions. This means that since it does not totally dissociate i.e. 100%, it is a WEAK BASE.
Answer:
It is a weak base.
Explanation:
Guy above me is right and I took the test :)
Un elemento X, del grupo I A, reacciona con un elemento Y, del grupo VI A. Señalar cuáles de las siguientes afirmaciones son correctas y cuáles no, justificando en todos los casos:
a) X es un metal
b) Y es un metal
c) La fórmula del compuesto es XY2
d) El compuesto es iónico
When naming a molecule, how do you indicate that the carbons on either side
of the double bond are pointing in opposite directions?
Answer:
use the prefix trans-
When naming a molecule, we indicate that the carbons on either side of the double bond are pointing in opposite directions by adding a prefix (-trans) in the name of the molecule.
What is IUPAC nomenclature?IUPAC nomenclature of organic compounds refers to the systematic approach taken for the nomenclature of organic compounds as per the recommendation of the International Union of Pure and Applied Chemistry.
If alkenes have two different substituents at each end of the C=C then they can exist as stereoisomers (as geometric isomers).
This is because there is restricted rotation of the double bond due to the pi bond which means they don't readily interconvert.
cis- if the two alkyl groups, R-, are on the same side of the C=Ctrans- if the two alkyl groups, R-, are on opposite sides of the C=C.Therefore, When naming a molecule, we indicate that the carbons on either side of the double bond are pointing in opposite directions by adding a prefix (-trans) in the name of the molecule.
Learn more about IUPAC Nomenclature, here:
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When a chemical reaction occurs,____.
Answer:
when chemical bonds between atoms are formed or broken
This woman comes to the clinic with high blood pressure,
hyperglycemia(high blood sugar), weakening of the bones and severe
depression of the immune system. Can you diagnose her condition?
249 g of potassium iodide, KI, is mixed with 496.5 g of lead(II) nitrate, Pb(NO3)2.
The equation of the reaction is represented below.
[Pb(NO3)2 = 331; KI = 166; PbI2 = 461, KNO3 = 101]
Calculate the number of moles of excess reagent left.
Give your answer to three significant figures.
Answer: The number of moles of excess reagent left is 0.750 moles
Explanation:
The number of moles is calculated by using the equation:
[tex]\text{Number of moles}=\frac{\text{Given mass}}{\text{Molar mass}}[/tex] ......(1)
For KI:Given mass of [tex]KI[/tex] = 249 g
Molar mass of [tex]KI[/tex] = 166 g/mol
Putting values in equation 1, we get:
[tex]\text{Moles of KI}=\frac{249g}{166g/mol}=1.5mol[/tex]
For [tex]Pb(NO_3)_2[/tex]:Given mass of [tex]Pb(NO_3)_2[/tex] = 496.5 g
Molar mass of [tex]Pb(NO_3)_2[/tex] = 331 g/mol
Putting values in equation 1, we get:
[tex]\text{Moles of }Pb(NO_3)_2=\frac{496.5g}{331g/mol}=1.5mol[/tex]
The given chemical equation follows:
[tex]2KI+Pb(NO_3)_2\rightarrow 2KNO_3+PbI_2[/tex]
By stoichiometry of the reaction:
If 2 moles of KI reacts with 1 mole of lead(II) nitrate
So, 1.5 moles of KI will react with = [tex]\frac{1}{2}\times 1.5=0.75mol[/tex] of lead(II) nitrate
As the given amount of lead(II) nitrate is more than the required amount. Thus, it is present in excess and is considered as an excess reagent.
Thus, KI is considered a limiting reagent because it limits the formation of the product.
Moles of excess reactant ([tex]Pb(NO_3)_2[/tex]) left = [1.5 - 0.75] = 0.750 moles
Hence, the number of moles of excess reagent left is 0.750 moles
