To make a buffer using a strong base, dissolve it in water, then add a weak acid, reacting some of the base to form the conjugate base. This weak acid-conjugate base pair provides the buffering action, resisting significant pH changes when small amounts of strong acid or base are added.
Explanation:To create a buffer solution using a strong base and another reagent, we can follow a straightforward process. A common and illustrative example is using sodium hydroxide (NaOH), a strong base, and a weak acid such as acetic acid (CH3CO2H). First, we prepare a solution of the strong base by dissolving it in water. Then we add the weak acid to the solution. The weak acid will react with some of the hydroxide ions (OH-) from the strong base to form water (H2O) and the weak acid's conjugate base. In this case, sodium acetate (CH3CO2Na) is produced in the reaction:
CH3CO2H(aq) + OH-(aq)
ightarrow H2O(l) + CH3CO2-(aq)
When a strong acid like hydrochloric acid (HCl) is added to this buffer solution, it will react with the acetate anion to form more acetic acid, rather than causing a significant change in pH:
HCl(aq) + CH3CO2-(aq)
ightarrow H2O(l) + CH3CO2H(aq)
Finally, adding more strong base such as NaOH will cause the reverse reaction where the OH- ions are used up to create water and the acetate ion:
NaOH(aq) + CH3CO2H(aq)
ightarrow H2O(l) + CH3CO2Na(aq)
It is the presence of both a weak acid and its conjugate base that allows the buffer to maintain a relatively constant pH when small quantities of strong acids or bases are added. The creation of the conjugate base from the strong base and weak acid reaction is crucial for creating a functioning buffer solution.
Using the periodic table, which of the following elements has the most properties in common with calcium (Ca)?
scandium (Sc)
argon (Ar)
potassium (K)
magnesium (Mg)
atoms are made of 3 types of sub atomic particles; electrons, protons and neutrons
Of these particles, electrons are involved in the chemical reactions.
Therefore chemical properties of the element are determined by the electrons, and that too mostly the valence electrons. Valence electrons are the electrons in the outermost energy shell.
Atoms with same number of valence electrons have similar chemical properties. atoms having same number of valence electrons are classified into groups.
So elements of the same group have same number of valence electrons, hence similar chemical properties
Ca has 2 valence electrons so it belongs to group 2. Of the given elements
only Mg belongs to group 2. Therefore Mg has the most common properties with Ca
Balance the equation, if necessary, for the reaction between iron and oxygen.
Fe + O₂ → Fe₂O₃
Answer:
[tex]4Fe+3O_2\rightarrow 2Fe_2O_3[/tex]
Explanation:
The unbalanced reaction of the reaction between iron and oxygen is shown below as:-
[tex]Fe+O_2\rightarrow Fe_2O_3[/tex]
On the left hand side,
There is 1 iron atom and 2 oxygen atoms
On the right hand side,
There are 2 iron atoms and 3 oxygen atoms
Thus,
Right side, [tex]Fe_2O_3[/tex] is multiplied by 2.
Left side, [tex]O_2[/tex] must be multiplied by 3 and [tex]Fe[/tex] by 4 so to balance iron and oxygen.
Thus, the balanced reaction is:-
[tex]4Fe+3O_2\rightarrow 2Fe_2O_3[/tex]
Which of the following elements is a metal?
carbon (C)
iodine (I)
iridium (Ir)
radon (Rn)
Iridium (Ir) is a element which is metal. Therefore, the correct option is option C among all the given options.
What is metal?Metal is any of a group of substances with strong thermal and electrical conductivity, malleability, ductility, as well as high light reflection. Typically, metals are crystalline solids. The free-electron hypothesis provides the best justification for the high thermal and electrical conductivity and high of the simple elements.
They typically have a very straightforward crystal structure that is characterized by dense atom packing and a high level of symmetry. Metal atoms often have fewer than half of their total number of electrons in the outermost shell. This property makes metals less likely to combine to create compounds. Iridium (Ir) is a element which is metal.
Therefore, the correct option is option C. Iridium (Ir) is a element which is metal.
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Which of the following statements is true about catalysts? and Why?
a. Catalysts slow down the rate of chemical reactions
b. All catalysts are enzymes
c. Catalysts are used up during a chemical reaction
d. Catalysts lower the activation energy of a chemical reaction
Your answer will be C. It's not D i just took the test
What mass of steam at 100 C must be mixed with 150 gram of ice at its melting point, in a thermally insulated container, to produce liquid water at 50 C?
Heat of fusion of water at its normal freezing or melting temperature = 333 kJ/kg
Heat of vaporization (or steam) = 2256 kJ/kg
Specific heat of water = 4180 J/kg K ...?
Which has a higher frequency, a neutron or electron? Why?
How many times does the digit 1 appear in the number 500, solution please
...?
how many atoms are in a cracker
I need help! how many moles are in 3.4*10^-7 grams of silicon dioxide, SiO2. I got 2.0^17 but I think it's wrong :(
What is the conversion of 160g to cg?
One success of Johann Döbereiner's law of triads was that it organized most of the known elements into three-element groups based on similarities in their properties. (Points : 2)
True
False
Answer:
True.
Explanation:
In 1824, the German chemist Johann Dobereiner, when analyzing the chemical elements calcium (Ca), strontium (Sr) and barium (Ba), noticed a simple relationship between their atomic masses: the mass of the strontium atom was very close to mass average of the other two elements. This observation was named the Triads of Chemical Elements and thus was born the law of the triads of Johann Döbereiner.
This law argued that elements with similar properties, ie, which reacted similarly with other elements, were organized in groups of three.
what is the chemical formula for fluorine in standard state?
Final answer:
The chemical formula for fluorine in its standard state is F₂, which is a diatomic gas due to fluorine's high electronegativity.
Explanation:
The chemical formula for fluorine in its standard state is F₂. Fluorine is a diatomic molecule, meaning it naturally pairs up with another fluorine atom to form a molecule in its most stable and common form, denoted as F₂ gas. Rule 3 of assigning oxidation states is vital for fluorine due to its strong electronegativity, which is the highest among all elements. Thus, the F-F molecule can provide a reference point for calculating oxidation states of other elements.
When applying heat to a substance changes the form, but not the identity of the substance, this is evidence of:
a chemical change
a physical change
no change
an anthropomorphic change
Answer:
This is the evidence of physical change.
Explanation:
When the substance is heated, its form is changed but identity remain the same, it is then a physical change. In physical change substance can only change their phases but not lose the identity. For example it may change its state from solid to liquid and liquid to gas.
Physical change:
The changes that occur only due to change in shape or form but their chemical or internal composition remain unchanged.
These changes were reversible.
They have same chemical property.
These changes can be observed with naked eye.
Example s:
Water converting to Ice .
Water converting to gas.
In this water molecule remain the same only they rearrange themselves that change its state of mater not composition.
Chemical change:
The changes, that occur due to change in the composition of a substance and result in a different compound is known as chemical change.
These changes are irreversible .
These changes occur due to chemical reactions .
These may not be observed with naked eye .
Examples:
combustion of fuel or wood: that oil or wood convert into energy, CO2 and ash in case of wood .
Boiling of egg: that change the chemical composition of protein in the egg
What is the difference between the electron shells, the subshells, and the orbitals?
If 4.00 moles of gasoline are burned, what volume of oxygen is needed if the pressure is 0.93 ATM, and the temperature is 35.0 degrees Celsius?
A gaseous hydrogen and carbon containing compound is decomposed and found to contain 82.66% carbon and 17.34% hydrogen by mass. The mass of 158 mL of the gas, measured at 556 mmHg and 25 ∘C, was found to be 0.275 g. What is the molecular formula of the compound?
To find the molecular formula of a compound, one must first determine the empirical formula based on mass percentages, calculate the molar mass using the ideal gas law, and then compare the empirical formula mass with the molar mass.
Explanation:To establish the molecular formula for the gaseous compound, we start by calculating its empirical formula using the percentages given: 82.66% carbon (C) and 17.34% hydrogen (H). With the assumption of a 100 g sample, we have 82.66 g of C and 17.34 g of H. Converting these masses to moles, we use the atomic mass of carbon (12.01 g/mol) and hydrogen (1.01 g/mol), yielding:
The empirical formula is obtained by dividing by the smaller number of moles:
Since we cannot have half a hydrogen in a formula, we multiply by 2 to get whole numbers, giving us an empirical formula of C2H5. Next, we calculate the molar mass (MM) using the provided conditions (158 mL at 556 mmHg and 25
C with a mass of 0.275 g). We apply the ideal gas law:
PV = nRT
Converting the pressure to atmospheres (556 mmHg / 760 mmHg/atm) and the volume to liters (158 mL / 1000 mL/L), and using the value of R (0.0821 Latm/molk), the molar mass can be calculated. Finally, comparing the empirical formula mass (EM) to the MM obtained allows for the determination of the molecular formula by finding the ratio between MM and EM, which tells us how many empirical units are in the molecular formula.
To summarize:
The atomic weight of hydrogen is
1?
The atomic weight of hydrogen is approximately 1 atomic mass unit. It is the lightest element with an atomic number of 1 and it consists mainly of one proton and one electron. The atomic weight represents the weighted average atomic mass of hydrogen's isotopes.
The atomic weight of hydrogen is often considered to be 1. This value is based on a standard atomic weight scale where hydrogen, the lightest element with the atomic number, Z, of 1, sets the reference point for the scale. The atomic mass of hydrogen is approximately 1 atomic mass unit (u), which is a unit derived from the mass of a carbon-12 atom. Since a hydrogen atom consists of one proton and one electron, and has no neutrons, its atomic mass is very close to 1 u. The actual mass of a hydrogen atom is about 1.7 x 10⁻²⁷ kg. However, in chemical reactions and on the periodic table, a weighted average of the atomic masses of the different isotopes of hydrogen (such as protium with no neutrons, deuterium with one neutron, and tritium with two neutrons) is used, leading to a slightly different average atomic mass of approximately 1.008. It is critical in chemistry to distinguish between the atomic number, which is the number of protons in the nucleus of an atom, and the atomic mass or atomic weight, which is the weighted average mass of an atom's isotopes as they occur naturally.
What is the driving force for water to freeze below 0 degree C? what is the driving force for ice to melt above 0 degree C? ...?
Explanation:
When the water freezes, the variable which changes is the temperature because as we reduce the temperature, the particles will come closer to each other and the average kinetic energy of the particles of water decreases. Hence, the water freezes below 0°C.
In the case of melting, the temperature is increased which means that the particles move away from each other and the average kinetic energy of the particles of water at this temperature increases. Hence, the water melts above 100°C.
which of the following is a good scientific hypothesis
A. plants grow towards windows because the sun provides the food they need.
B. if sunlight causes skin cancer, the people should stay put of the sun.
C. plants that don't get sunlight will die.
D. if a plant is exposed to only blue light, the plant will grow more slowly
A testable, precise prediction of what you believe will occur in a scientific experiment that is based on your observations and past knowledge is called a scientific hypothesis. Here the correct option is D.
A scientific theory must satisfy two requirements in order to be accepted: it must be testable and falsifiable. A theory is not scientific if it cannot be verified through observation. A hypothesis is a rough explanation for a group of facts that can be put to the test by specific follow-up research.
Among the given options, if a plant is exposed to only blue light, the plant will grow more slowly can be proved by performing an experiment. Thus it is an example of a scientific hypothesis.
Thus the correct option is D.
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Pierce conducts an experiment in which waves collide in a way that the energy increases, which means that has occurred
It means the waves collides and constructive interference occurred.
Explanation:If the two waves coming from the opposite direction collide with each other, there are two way of their interference.
Constructive interference: An interference which results in the increase in energy. And it is when crust of a wave comes on the crust of second wave.Destructive interference: An interference which results in decrease in energy of the resulting wave and colliding waves cancel the result of each other.Hence in experiment there will be constructive interference.
Answer:
C.
Explanation:
I took the test!
Water has a density of 0.997 g/cm^3 at 25 degrees C; ice has a density of 0.917 g/cm^3 at -10 degrees C. (question part a) If a soft drink bottle whose volume is 1.50L is completely filled with water and then frozen to -10 degrees C, what volume does the ice occupy? (question part b) Can the ice be contained within the bottle?
"The density of the water is given by the mass and the volume." The volume occupied by water is 1.63 L and ice cannot be contained in water as it has more volume.
What are volume and density?Volume has been inversely related to the density as increased volume decreases the density by their inverse relation. The division of the mass and volume gives the density of the substances.
Given,
Density of water = 0.997 g/cm³
Density of ice = 0.917 g/cm³
The volume of the soft drink bottle = 1.50 L
The volume of ice is calculated as:
Volume = mass ÷ density
V = 1495.5 ÷ 0.917
= 1630 cm³
The unit conversion is done as:
1 cm³ = 1 mL
1630 cm³ = 1630 mL = 1.630 L
Ice cannot be fitted into the soft drink bottles as the volume of ice 1.63 L is more than the volume of the bottle, 1.50 L.
Therefore, the volume of ice is 1.630 L.
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Which statement defines the heat capacity of a sample? the temperature of a given sample the temperature that a given sample can withstand the quantity of heat that is required to raise the sample’s temperature by 1°C (or Kelvin) the quantity of heat that is required to raise 1 g of the sample by 1°C (or Kelvin) at a given pressure
Answer is: the quantity of heat that is required to raise the sample’s temperature by 1°C (or Kelvin).
Heat capacity of a sample is expressed in units of thermal energy per degree temperature (J/K).
Heat capacity is often defined relative to a unit of mass (J/kg·K or J/g·K), prefixed with the term specific.
For example, specific heat capacity of water is 4.184 J/g·K (Cp(H₂O) = 4.184 J/g·K).
The statement that defines the heat capacity of a sample is the quantity of heat that is required to raise the sample’s temperature by 1°C (or Kelvin).
WHAT IS HEAT CAPACITY?Heat capacity of a substance refers to the quantity of heat that is required to raise the temperature of the substance by 1°C or K.
The heat capacity of a substance can be measured in Jg/°C or JK/g.
The heat capacity of water molecule is 4.184 Jg/°C.
Therefore, the statement that defines the heat capacity of a sample is the quantity of heat that is required to raise the sample’s temperature by 1°C (or Kelvin).
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A large sac that stores water,salts and other materials for the cell is called a
the modern periodic table is arranged in order of increasing atomic
The modern periodic table arranges elements in order of increasing atomic number, which corresponds to the number of protons in an atom's nucleus. The increasing atomic number across the table helps predict properties and interactions of elements.
Explanation:The modern periodic table is an essential tool in chemistry, used to catalog and organize the known elements. The table is arranged in order of increasing atomic number, which is equivalent to the number of protons in an atom's nucleus.
For instance, Hydrogen has an atomic number of 1 and is the first element on the table, while Helium has an atomic number of 2 and is the second element. As you move down and across the table, the atomic number continues to increase.
This help scientists to predict the properties of various elements, their reactivity, and how they might interact with other elements.
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How many moles of dipyrithione (C10H8N2O2S2) contain 8.2 x 10^24 atoms of N2?
Answer : The number of moles of dipyrithione are [tex]1.4\times 10^1[/tex] moles.
Explanation :
The given molecule is, [tex]C_{10}H_8N_2O_2S_2[/tex]
In this molecule, there are 10 atoms of carbon, 8 atoms of hydrogen, 2 atoms of nitrogen, 2 atoms of oxygen and 2 atoms of sulfur.
As we know that, 1 mole of substance contains [tex]6.022\times 10^{23}[/tex] number of atoms.
As, [tex]6.022\times 10^{23}[/tex] atoms of [tex]N_2[/tex] present in 1 mole of [tex]C_{10}H_8N_2O_2S_2[/tex]
So, [tex]8.2\times 10^{24}[/tex] atoms of [tex]N_2[/tex] present in [tex]\frac{8.2\times 10^{24}}{6.022\times 10^{23}}=13.6\approx 1.4\times 10^1[/tex] mole of [tex]C_{10}H_8N_2O_2S_2[/tex]
Therefore, the number of moles of dipyrithione are [tex]1.4\times 10^1[/tex] moles.
There are 6.8 moles of dipyrithione that contain 8.2 x 10²⁴ atoms of N₂, calculated using Avogadro's number and the composition of the molecule.
Avogadro's number (NA) is 6.022 x 10²³ mol⁻¹, which is the number of particles in one mole of a substance. Since each molecule of N₂ contains two nitrogen atoms, divide the total number of nitrogen atoms by two to find the number of N₂ molecules, and then divide by Avogadro's number to find the moles of N₂.
First, calculate the number of moles of N₂ by using the formula
[tex]n = \frac{N}{N_A}[/tex]
It relates the number of particles N to the number of moles n. In this case, N is the total number of nitrogen atoms given (8.2 x 10²⁴ atoms), which we divide by 2 to account for N₂, and then divide this number by Avogadro's number (6.022 x 10²³ mol-1) to find the moles of N₂:
nN2 = (8.2 x 10²⁴ atoms) / (2 x 6.022 x 10²³ mol⁻¹) = 6.8 moles of N₂
Since dipyrithione has one N₂ unit per molecule, the number of moles of dipyrithione is the same as the number of moles of N₂:
6.8 moles of dipyrithione will contain 8.2 x 10²⁴ atoms of N₂.
Where does a mid ocean ridge form?
Calculate the number of atoms in 4.2 moles of sulfur atoms.
Now, calculate the mass of these same 4.2 moles.
Please show work! I have no clue how to solve this.
Final answer:
To calculate the number of atoms in 4.2 moles of sulfur atoms, use Avogadro's number. To calculate the mass of these 4.2 moles, multiply the number of moles by the molar mass of sulfur.
Explanation:
To calculate the number of atoms in 4.2 moles of sulfur atoms, you can use Avogadro's number. Avogadro's number is equal to 6.022 x 10^23 atoms per mole. So, by multiplying the number of moles (4.2) by Avogadro's number, you can determine the number of atoms:
Number of atoms = 4.2 moles * (6.022 x 10^23 atoms/mole) = 2.53 x 10^24 atoms.
To calculate the mass of 4.2 moles of sulfur atoms, you need to know the molar mass of sulfur. The molar mass of sulfur is 32.07 g/mol. Multiply the number of moles by the molar mass to find the mass:
Mass = 4.2 moles * 32.07 g/mol = 134.754 g.
Why does the potassium atom tend to lose only one electron?
.
What happens when nitrogen fills its valence shell?
What happens when nitrogen fills its valence shell is that 3 electron are gained creating N3- ion
calculation
According to octet rule atom tend to have a total of 8 electrons in its valence shell Nitrogen is a non metal which is in atomic number 7.The electron configuration of nitrogen is 1S2 2S2 2P3 or [He] 2S2 2P3 or 2.5.. from the electron configuration above Nitrogen has 5 valence electrons, therefore it require to gain 3 electron in order to fill its valence shell. when 3 electrons are gained Nitrogen create N3- ion.Fe(NO3)2 not sure how to get the oxidation numbers of all elements
Final answer:
To find the oxidation numbers in Fe(NO3)2, we acknowledge that the sum is zero for a neutral compound. Each nitrate ion has an oxidation number of -1; thus, nitrogen is +5, and each oxygen is -2. Therefore, iron must have an oxidation number of +2 to balance the negative charge of the two nitrates.
Explanation:
To determine the oxidation numbers of elements in Fe(NO3)2, we follow the general rules for oxidation states. First, we know that the chemical compound as a whole is neutral, so the sum of all oxidation numbers in Fe(NO3)2 must be zero. Secondly, the oxidation number of oxygen is typically -2. In each nitrate ion (NO3−), there are three oxygen atoms contributing to a total of -6. The nitrate ion has a charge of -1, which means the nitrogen must have an oxidation number of +5 to balance the -6 from the oxygen atoms (x + 3(−2) = −1, x = +5).
Since there are two nitrate ions in Fe(NO3)2, this gives us a total negative charge of -2 from both nitrate ions. Consequently, the iron (Fe) must have an oxidation number of +2 to neutralize the charge from the nitrates (Fe2+). Thus, the complete set of oxidation numbers in Fe(NO3)2 is Fe2+ and two NO3− ions, with nitrogen being +5 and oxygen -2 in each nitrate ion.