Answer:
=154.8 J
Explanation:
Change in enthalpy = MC∅ where M is the mass of the substance, C is the specific heat capacity and ∅ is the change in temperature.
Change in temperature = 100.0°C-20.0°C=80°C
ΔH=MC∅
The specific heat capacity of gold= 0.129 J/g°C
ΔH= 15.0g×0.129J/g°C×80°C
=154.8 J
To raise the temperature of a 15.0 gram sample of gold from 20.0°C to 100.0°C, approximately 154.8 joules of heat energy is required, using the formula q = mcΔT where c is the specific heat capacity of gold.
To calculate the heat needed to raise the temperature of gold, you can use the formula:
Q = mcΔT
Where Q is the heat, m is the mass of the gold, c is the specific heat capacity of gold, and ΔT is the change in temperature.
Calculate the change in temperature: ΔT = 100.0°C - 20.0°C = 80.0°C
Look up the specific heat capacity of gold, which is 0.129 J/g°C
Substitute the values into the formula: Q = 15.0g × 0.129 J/g°C × 80.0°C = 154.8 J
When does carbon dioxide absorb the most heat energy
Answer:Carbon dioxide absorbs the most heat energy during SUBLIMATION. By definition, sublimation is the transition of a substance from the solid to the gas phase without passing through the intermediate liquid phase. Hope this answers your question.
Explanation:
Answer:
sublimation
Explanation:
the concentration of the radio active isotope potassium-40 in a rock sample is found to be 6.25%. what is the age of the rock
Answer:
5.0 x 10⁹ years.
Explanation:
It is known that the decay of a radioactive isotope isotope obeys first order kinetics.Half-life time is the time needed for the reactants to be in its half concentration.If reactant has initial concentration [A₀], after half-life time its concentration will be ([A₀]/2).Also, it is clear that in first order decay the half-life time is independent of the initial concentration.The half-life of K-40 = 1.251 × 10⁹ years.For, first order reactions:k = ln(2)/(t1/2) = 0.693/(t1/2).
Where, k is the rate constant of the reaction.
t1/2 is the half-life of the reaction.
∴ k =0.693/(t1/2) = 0.693/(1.251 × 10⁹ years) = 5.54 x 10⁻¹⁰ year⁻¹.
Also, we have the integral law of first order reaction:kt = ln([A₀]/[A]),
where, k is the rate constant of the reaction (k = 5.54 x 10⁻¹⁰ year⁻¹).
t is the time of the reaction (t = ??? year).
[A₀] is the initial concentration of (K-40) ([A₀] = 100%).
[A] is the remaining concentration of (K-40) ([A] = 6.25%).
∴ (5.54 x 10⁻¹⁰ year⁻¹)(t) = ln((100%)/( 6.25%))
∴ (5.54 x 10⁻¹⁰ year⁻¹)(t) = 2.77.
∴ t = 2.77/(5.54 x 10⁻¹⁰ year⁻¹) = 5.0 x 10⁹ years.
Answer:
[tex]\boxed{4.99 \times10^{9} \text{ y}}[/tex]
Explanation:
The half-life of potassium-40 (1.248 ×10⁹ y) is the time it takes for half of it to decay.
After one half-life, half (50 %) of the original amount will remain.
After a second half-life, half of that amount (25 %) will remain, and so on.
We can construct a table as follows:
[tex]\begin{array}{cccc}\textbf{No. of} & &\textbf{Fraction} &\textbf{Percent}\\ \textbf{Half-lives} & \textbf{t/(10$^{9}$ y}) &\textbf{Remaining} &\textbf{Remaining}\\0 & 0 & 1 & 100\\\\1 & 1.248 & \dfrac{1}{2} & 50\\\\2 & 2.496 & \dfrac{1}{4} & 25\\\\3 & 3.744 & \dfrac{1}{8} & 12.5\\\\4 & 4.992 & \dfrac{1}{16} & 6.25\\\\5 & 6.240 & \dfrac{1}{32} & 3.125\\\\\end{array}[/tex]
We see that after four half-lives, ¹/₁₆ or 6.25 % of the original mass remains.
Conversely, if 6.25 % of the sample remains, the age of the sample must be four half-lives.
[tex]\text{Age of rock} = 4 \times 1.248 \times 10^{9}\text{ y}= \boxed{\mathbf{4.99 \times 10^{9}} \textbf{ y}}[/tex]
How many moles of air are there in a 3 L container at 1 atm pressure and 294 K?Use PV=nRT
The ideal gas law states: [tex]PV=nRT[/tex]
If we put in the data.
[tex]
1\cdot7=n\cdot8.31\cdot294 \\
n=\boxed{2.865\cdot10^{-3}mol}=\boxed{2.865mmol}
[/tex]
Hope this helps.
r3t40
Using the ideal gas law PV = nRT, the number of moles of air in a 3 L container at 1 atm and 294 K is calculated to be approximately 0.124 moles.
Calculating Moles of Air Using the Ideal Gas Law
To find the number of moles of air in a 3 L container at 1 atm pressure and 294 K, we can use the ideal gas law, PV = nRT. We are given the following values: P (pressure) = 1 atm, V (volume) = 3 L, T (temperature) = 294 K. We can use R (the ideal gas constant) = 0.08206 L-atm/mol-K, which is appropriate for the units provided.
Step-by-step solution:
Rearrange the ideal gas law formula to solve for n (moles of gas): n = PV / RT.Plug in the known values: n = (1 atm)After doing the math, we find that the number of moles n of air is approximately 0.124 moles.
Schrodinger and Heisenberg developed an alternate theory about atomic nature that contradicted some of Bohr's model of the atom. How do changes resulting from new technology and evidence affect the reputation of the atomic theory?
Answer:
They don't affect the reputation of atomic theory at all.
Explanation:
Schrödinger and Heisenberg extended the model of the atom, as did Thompson, Rutherford, and Moseley before them.
Each model was based on the best available information at the time.
The availability of new information may require a new atomic model, but it doesn't destroy the reputation of older ones.
Answer: it did not affect the reputation of the atomic theory
Explanation:
Bohr only considered hydrogen and hydrogen-like atoms. Atoms with one electron. Schrödinger and Heisenberg extended it.
Every knowledge is science is alway built from previous knowledge. What you know to be right today might be proven wrong by someone else in the future. It doesn't mean you weren't right. So all scientists must keep an open mind, who knows, we might encounter aliens on earth in the future.
Which term describes something that changes during an experiment?
Answer:
Dependent variable
Explanation:
Answer:
A variable
Explanation:
A variable is data that changes, two examples are an independent variable and a dependent variable.
Which element below could be an isotope of beryllium
sodium-10
beryllium-10
boron-9
carbon-9
Answer:
beryllium
Explanation:
isotopes are same elements
Answer:
beryllium-10
Explanation:
First let's remember what an isotope is
Isotopes are atoms of the same element, whose nucleus have a different amount of neutrons, and therefore, differ in mass number .
Since isotopes are atoms of the same element, the only option that corresponds to beryllium is the option beryllium-10
Which of these expressions are correct variations of the Combined Gas Law? P1V1T2 = P2V2T1 both
Answer:
Explanation:
The combined gas law is also known as general gas law and it is the reduction of the ideal gas equation. In the combined gas law, we assume that n= 1
From PV=nRT
[tex]\frac{PV}{T}[/tex] = R (constant) if n= 1
∴ [tex]\frac{P_{1} V_{1} }{T_{1} }[/tex] = [tex]\frac{P_{2} V_{2} }{T_{2} }[/tex] = [tex]\frac{P_{n} V_{n} }{T_{n} }[/tex]
Answer: Both!
Explanation:
When determining the shape of a molecule, it is important to draw a Lewis Dot structure first in order to see the total number of...?
A. electrons within the molecule
B. bonding and unshared pairs around central atom
C. unshared pair within the molecule
(PLEASE HELP I REALLY NEED IT )
Answer : The correct option is, (B) bonding and unshared pairs around central atom.
Explanation :
Lewis-dot structure : It shows the bonding between the atoms of a molecule.
When we are determining the shape of a molecule then it is important to draw a Lewis-dot structure and for drawing a Lewis-dot structure we should know that how many total number of valance electrons present in a given compound or a molecule.
For example:
The given molecule is, [tex]H_2CO_3[/tex]
As we know that hydrogen has '1' valence electrons, carbon has '4' valance electrons and oxygen has '6' valence electron.
Therefore, the total number of valence electrons in [tex]H_2CO_3[/tex] = 2 + 4 + 18 = 24
Now we have to determine the hybridization of carbon in [tex]H_2CO_3[/tex]
Number of bond pairs = 3
Number of lone pairs = 0
Number of atomic orbitals around carbon atom = 3 + 0 = 3
So, hybridization will be [tex]sp^2[/tex] and the shape is, trigonal planar.
Hence, it is important to draw a Lewis Dot structure first in order to see the total number of bonding and unshared pairs around central atom.
What part of Dalton’s atomic theory was later proved to be incorrect?
Answer:
D
Explanation:
It was later identified that atoms of the same element can be different. This is mostly seen in elements with different isotopes. An example is carbon-14 and carbon-12 that have different masses due to differences in neutrons numbers in their nuclei.
Atoms are also divisible into subatomic particles. Today, atoms can be smashed apart into neutrons, protons and electrons particles. This also occurs naturally in radioactive decay.
It was later identified that atoms of the same element can be different. This is mostly seen in elements with different isotopes. The correct option is D.
Thus, An example is carbon-14 and carbon-12 that have different masses due to differences in neutrons numbers in their nuclei.
Atoms are also divisible into subatomic particles. Today, atoms can be smashed apart into neutrons, protons and electrons particles. This also occurs naturally in radioactive decay.
John Dalton, an English physicist and chemist, proposed the atomic hypothesis in 1808 as a scientific theory about the composition of matter. It claimed that tiny, indivisible particles called "atoms" make up all substance.
According to Dalton's atomic theory, atoms, which are indestructible and indivisible building blocks, make up all substances. Unlike other elements, which have atoms of different sizes and weights, an element's atoms have all the same size and mass.
Thus, It was later identified that atoms of the same element can be different. This is mostly seen in elements with different isotopes. The correct option is D.
Learn more about element, refer to the link:
https://brainly.com/question/31950312
#SPJ6
Chains of amino acids make which can join together to make a
Answer:
Polypeptide chain
WHICH OF THE FOLLOWING WILL RESULT FROM INCREASING THE TEMPERATURE OF A GAS - APEX
Answer:
it will stay a gas
Explanation:
by heating up a gas you are making sure the gas stays a gas
How many moles of sodium chloride can react with 18.3 liters of fluorine gas at 1.2 atmospheres and 299 Kelvin?
Answer:
1.79 mol.
Explanation:
For the balanced reaction:2NaCl + F₂ → 2NaF + Cl₂.
It is clear that 2 mol of NaCl react with 1 mol of F₂ to produce 2 mol of NaF and 1 mol of Cl₂.
Firstly, we can get the no. of moles of F₂ gas using the general law of ideal gas: PV = nRT.where, P is the pressure of the gas in atm (P = 1.2 atm).
V is the volume of the gas in L (V = 18.3 L).
n is the no. of moles of the gas in mol (n = ??? mol).
R is the general gas constant (R = 0.0821 L.atm/mol.K),
T is the temperature of the gas in K (299 K).
∴ no. of moles of F₂ (n) = PV/RT = (1.2 atm)(18.3 L)/(0.0821 L.atm/mol.K)(299 K) = 0.895 mol.
Now, we can find the no. of moles of NaCl is needed to react with 0.895 mol of F₂:Using cross multiplication:
2 mol of NaCl is needed to react with → 1 mol of F₂, from stichiometry.
??? mol of NaCl is needed to react with → 0.895 mol of F₂.
∴ The no. of moles of NaCl needed = (2 mol)(0.895 mol)/(1 mol) = 1.79 mol.
The ideal gas constant, R has several different values that could be used. Which quantity causes these differences?
pressure
temperature
volume
moles
Answer: Pressure
Explanation:
The pressure is sometimes measured in different units
Answer:
pressure
Explanation:
The different values of R are as follows:
R = 0.0821 liter•atm/mol•K.
R = 62.3637 L•Torr/mol•K or L•mmHg/mol•K.
Here the different units of pressure are atm, Torr and mmHg.
The unit of volume, temperature and moles are Liter (L), Kelvin (K) and mol respectively.
When different values of Pressure are used and expressed in different units that cause a change in the value of R.
A sample of neon has a volume of 5.00 L, and initial temperature of 425 K, and an initial pressure of 1.23 atm. If the final temperature is 288 K, and the final volume is 0.555 L, what is the final pressure?
5.04 atm
7.51 atm
1.82 atm
9.08 atm
Answer:
7.51
Explanation:
general gas law
the product of pressure and volume is divided by absolute temperature
PLEASE HELP ASAP
which of the following are examples of chemical changes
-silver tarnishes
- a sheet of copper is pounded into the shape of a bowl
- barium melts at 725° C
- Hydrogen reacts with oxygen to form water
Answer: Hydrogen reacts with oxygen to form water
Explanation: Chemical changes are those which changes the identity of the chemical nature of any substance.
Thus out of the given options , the correct one is the formation of the water molecule when hydrogen reacts with oxygen as it is changing the identity of hydrogen and oxygen atoms to form a molecule of water.
The rest of the three options belongs to the category of the physical changes in which the chemical nature of any substance has not been changed but only the properties which an be easily observed can be changed.
Which one of the following is a balanced equation?
O A. 2NH3 (g) + 3Mg (s) - 3H2 (g) + Mg3N2 (s)
OB. 4NH3 (9) + Mg(s)* - H2(g) + Mg3N2 (s)
OC. NH3 (9) + Mg (s) - H2 (9) + Mg3N2 (s)
O D. Ca (s) + 02 (9) - 2Cao (s)
Answer: OA is a balanced equation.
Explanation: For an equation to be balanced, the number of atoms and the total charge of each element in the reaction, of the product and reactant side must be the same.
Considering OA; 6 atoms of nitrogen is present in the reactant side. Shifting to the product side, 6 atoms of nitrogen is also present. Taking the other element in the reaction into account, the number of atoms of each element balances on both sides.
ANSWER:
The correct answer is OA. 2NH3 (g) + 3Mg (s) →3H2 (g) + Mg3N2 (s)
The Equation; 2NH3 (g) + 3Mg (s) →3H2 (g) + Mg3N2 (s), is a balanced chemical equation.
FURTHER EXPLANATION;
According to the law of conservation of mass, all chemical equations should be written such that the mass of the reactants is equal to the mass of the products.
This is done by balancing the chemical equation.
Balancing of chemical equations is a try and error method that makes sure the number of atoms of each element in a chemical equation are equal on the side of the reactants and that of products.
The equation; 2NH3 (g) + 3Mg (s) →3H2 (g) + Mg3N2 is said to be balanced since the number of atoms of each element are equal on both side of the equation.
That is; 2 atoms of nitrogen, 6 atoms of hydrogen and 3 atoms of magnesium on both side of the equation.
Choice OB is incorrect because, the equation 4NH3 (g) + Mg(s)* - H2(g) + Mg3N2 (s) is not balanced as the number of nitrogen atoms and that of hydrogen atoms are not equal on both side of the equation.(4 nitrogen atoms on the reactant side and 2 nitrogen atoms on the product side, 12 hydrogen atoms on the reactant side and 2 hydrogen atoms on the product side).
Choice OC is incorrect because, the equation, NH3 (g) + Mg (s) - H2 (g) + Mg3N2 (s) is not balanced as the number of nitrogen atoms, magnesium atoms and that of hydrogen atoms are not equal on both side of the equation.(1 nitrogen atom on the reactant side and 2 nitrogen atoms on the product side, 3 hydrogen atoms on the reactant side and 2 hydrogen atoms on the product side, 1 magnesium atom on the reactant side and 3 magnesium atom on the product side).
Choice OD is incorrect because, the equation Ca (s) + 02 (9) - 2Cao (s) is not balanced as the number calcium atoms is not the same on both side of the equation, 1 calcium atom on the reactant side and 2 calcium atoms on the product side.
what amount in moles does 242 L of carbon dioxide occupy at 1.32 atm and 20 degrees C
Answer:
13.28 mol.
Explanation:
We can use the general law of ideal gas: PV = nRT.where, P is the pressure of the gas in atm (P = 1.32 atm).
V is the volume of the gas in L (V = 242.0 L).
n is the no. of moles of the gas in mol (n = ??? mol).
R is the general gas constant (R = 0.0821 L.atm/mol.K).
T is the temperature of the gas in K (T = 20.0° + 273 = 293.0 K).
∴ n = PV/RT = (1.32 atm)(242.0 L)/(0.0821 L.atm/mol.K)(293.0 K) = 13.28 mol.
Recognizing the Properties of Water
Water has a "bent" geometry. Which explanation
does not explain why?
o Water's oxygen has unbonded electron pairs
that repel each other.
Water can form hydrogen bonds.
Electrons are evenly distributed in the water
molecule.
DO NE
Answer:
1. c
2.b
Explanation:
During metamorphic processes, increased pressure and temperature can affect the _______ of minerals in rock. Rocks subjected to very high pressure are typically _______ than others because mineral grains are squeezed together, and the atoms are more closely packed. During metamorphic processes, water facilitates the transfer of ions between and within minerals, which can _______ the rate at which metamorphic reactions take place. The growth of new minerals within a rock during metamorphism has been estimated to be about _______ per million years. _______ metamorphism is commonly associated with convergent plate boundaries, where two plates move toward each other. During contact metamorphism, a large intrusion will contain _______ thermal energy and will cool much more slowly than a small one. Metamorphosed sandstone is known as _______. The metamorphic rock _______, made from metamorphosed shale, was once used to make blackboards for classrooms.
Answer:
1.) stability
2.) denser
3.) increase
4.) 1 millimeter
5.) regional
6.) more
7.) quartzite
8.) slate
Explanation:
Answer:
Stability , Denser, Increase, 1 millimetre, Regional, More, Quartzite, Slate
Explanation:
During metamorphic processes, increased pressure and temperature can affect the stability of minerals in rock. Rocks subjected to very high pressure are typically denser than others because mineral grains are squeezed together, and the atoms are more closely packed. During metamorphic processes, water facilitates the transfer of ions between and within minerals, which can increase the rate at which metamorphic reactions take place. The growth of new minerals within a rock during metamorphism has been estimated to be about 1 millimeter per million years. Regional metamorphism is commonly associated with convergent plate boundaries, where two plates move toward each other. During contact metamorphism, a large intrusion will contain more thermal energy and will cool much more slowly than a small one. Metamorphosed sandstone is known as quartzite. The metamorphic rock slate, made from metamorphosed shale, was once used to make blackboards for classrooms.
What can a drop of liquid mercury be described as?
Answer:
a pure substance and an element
Explanation:
A drop of liquid mercury be described as a pure substance and an element.
Mercury is one of the known elements in the periodic table. The drop of liquid mercury is pure since it has constant and definite composition as well as distinct chemical properties.
A drop of liquid mercury can be described as dense, metallic, and silver. It remains liquid at room temperature due to its low melting point, has high surface tension leading to spherical drops, and is significantly denser than water.
A drop of liquid mercury can be described as a dense, metallic liquid that is silver in color. It is unique among metals because it has a melting point of -38.83 degrees Celsius (-37.89 degrees Fahrenheit), which allows it to be liquid at room temperature. Mercury has a high surface tension, which causes it to form spherical droplets when placed on a surface.
Because mercury does not wet most other materials, it often forms a strong meniscus when in a container, which is the curved surface you see at the top of the liquid. Additionally, mercury has a high density, about 13.6 times that of water, which explains its heavy weight even in small amounts. This high density also means that objects that would normally sink in water might instead float on a surface of mercury.
As a reminder, while mercury is fascinating to study and observe, it is also toxic and can lead to mercury poisoning if handled improperly. Mercury exposure must always be minimized, and any mercury spills should be addressed with appropriate safety protocols.
if you have 560 grams of magnesium. what mass of magnesium oxide will be produced?
Answer:
=933.3 grams
Explanation:
Magnesium reacts with oxygen producing magnesium oxide according to the following equation.
2Mg₍s₎ + O₂₍g₎→ 2MgO₍s₎
From the above equation, 2 moles of Magnesium produces 2 moles of magnesium oxide. Therefore the ratio of magnesium to magnesium oxide produced is 1:1
1 mole of magnesium oxide has a mass of: 24+16 =40 grams
560 grams of magnesium=560/24 moles
=70/3 moles.
Since the ratio is 1:1 the reaction produces 70/3 moles of magnesium oxide.
70/3 moles of MgO= 70/3 moles× 40 grams
=933.3 grams
Answer:
Here's what I get.
Explanation:
[tex]\begin{array}{lcccc}\textbf{(a)} \qquad \text{Na} & \text{reacts with} & \text{ diatomic chlorine}& \text{to form} & \text{sodium chloride}\\\textbf{(b)}\qquad \text{Na} & + & \text{Cl}_{2} & \longrightarrow \, & \text{NaCl}\\\textbf{(c)}\qquad \text{2Na}& + & \text{Cl}_{2} & \longrightarrow \, & \text{2NaCl}\\\end{array}[/tex]
(d) Mass of chlorine
(i) We know we will need an equation with masses and molar masses, so let’s gather all the information in one place.
M_r: 70.91 58.44
2Na + Cl₂ ⟶ 2NaCl
m/g: 117
(ii) Calculate the moles of NaCl
[tex]\text{Moles of NaCl} = \text{117 g NaCl} \times \dfrac{\text{1 mol NaCl}}{\text{58.44 g NaCl }} = \text{2.002 mol NaCl }[/tex]
(iii) Calculate the moles of Cl₂
The molar ratio is (1 mol Cl₂ /2 mol NaCl)
[tex]\text{Moles of Cl$_{2}$}= \text{2.002 mol NaCl} \times \dfrac{\text{1 mol Cl$_{2}$}}{\text{2 mol NaCl}} = \text{1.001 mol Cl$_{2}$}[/tex]
(iv) Calculate the mass of Cl₂
[tex]\text{Mass of Cl$_{2}$} = \text{1.001 mol Cl$_{2}$} \times \dfrac{\text{70.91 g Cl$_{2}$}}{\text{1 mol Cl$_{2}$}} = \text{71.0 g Cl$_{2}$}\\\\\text{The mass of chlorine needed is } \boxed{\textbf{71.0 g Cl$_{2}$}}[/tex]
An ionic solid is placed in water. which information is described by the solubility product constant?
A. the amount of precipitate that will form from the ions
B.the temperature at which the solid and its ions reach equilibrium
C.the equilibrium between the solid and its ions in solution
Answer:
[tex]\boxed{\text{C. the equilibrium between the solid and its ions in solution}}[/tex]
Explanation:
[tex]\rm MX(s) $\, \rightleftharpoons \,$ M$^{+}$(aq) + $^{-}$(aq); $K_{\text{sp}}$ = [M$^{+}$][X$^{-}$]\\\\\text{$K_{\text{sp}}$ gives us information on}\\\\\boxed{\textbf{ the equilibrium between the solid and its ions in solution}}[/tex]
It tells us nothing about the amount of precipitate that will form or the temperature at which the equilibrium occurs.
Answer: Option (C) is the correct answer.
Explanation:
An ionic solid is defined as the solid in which atoms are chemically combined together due to transfer of electrons.
As all ionic substances are soluble in water. So, when an ionic solid is dissolved in water then it will dissociate into ions.
As a result, an equilibrium will be maintained between the solid and its ions into the solution.
For example, [tex]AB(s) \rightleftharpoons A^{+} + B^{-}[/tex]
[tex]K_{sp} = \frac{[A^{+}]}{[B^{+}]}[/tex]
where, [tex]K_{sp}[/tex] = solubility product
Thus, we can conclude that the information described by the solubility product constant is that there is equilibrium between the solid and its ions in solution.
Iron pyrite, FeS2, is known as Fool's Gold because it is a shiny yellow solid which is similar in appearance to gold. Iron pyrite is an ionic compound. Gold is a metallic element.
- Iron pyrite, FeS2, contains positive and negative ions. The positive ion is Fe2+.
1) What is the formula of the negative ion?
Answer:
Explanation:
The algebraic sum of all the oxidation numbers of all atoms in a neutral compound is zero.
In order to know the formula of the negative Sulfur ion in pyrite, we must determine its oxidation state.
Let us make the make the oxidation number of sulfur = x
Therefore, FeS₂:
+2 +2x = 0
+2 = -2x
x = -1
The formula of the negative ion is S⁻
An experiment is conducted to see if cats preferred skim milk or 2% milk. A cup of skim milk
was put out for 5 kittens and then measured how much the kittens drank over the course of a
day. Following a cup of 2% milk was purout for the skittens and then masured how much the
kittens drank over the course of a day. The same kittens were used and the milk was served at
the same temperature. It was discovered that the cats liked the 2% milk more than the skim
milk. What is the dependent variable in this experiment?
its milk you cant do the experiment with out it.
Answer:
the quantity of milk drank by the kittens
Explanation:
Dependent variables are the actual variables a researcher sets out to determine during the course of an experiment. In order words, dependent variables are variables that are measured during experiments whose values fluctuate with the change of other variables.
In this case, a change in the type of milk given to the kittens affected the quantity of milk drank by the animals.
The actual variable being measured in this experiment is the amount to milk drank by the kittens.
Hence, the dependent variable is the quantity of milk drank by the kittens.
what is geography and importance of geography
Answer:
Meaning; Geography is a focus within the curriculum for understanding and resolving issues about the environment and sustainable development. It is also an important link between the natural and social sciences. As pupils study geography, they encounter different societies and cultures.
Importance; Geography is important because it contributes to our knowledge of the world and its phenomena. But, it also has an amazing practical side. For economists and managers, some types of engineering, farmers, architects, geopoliticians, generals and some knowledge of Geography is extremely important.
brainiest plz
Explanation:
Answer:
Geography is the physical features of places and landmarks around the globe.
Explanation:
Geography is important because it marks where places are, and geography can help you find you way.
Assigning Oxidation Numbers
QUICK CHECK
What are the oxidation numbers of the atoms in this reaction?
Check all that apply.
Mg(s) + 2HCl(aq) - MgCl2(aq) + H2(g
Mg = 0
H =+1
Cl= -1
Mg= +2
Cl=-1
H= 0
Answer:
B,C,D,E
Explanation:
Edge
Using a value of Ksp = 1.8 x 10-2 for the reaction PbCl2 Pb+2(aq) + 2Cl -(aq). If the value of Ksp was determined to be only 1.2 x 10-2: Too much solid has dissolved. Additional precipitate is forming. The solution is unsaturated. The ions are now combining to reduce their concentrations.
Answer:
The ions are now combining to reduce their concentrations.
Explanation:
For the chemical equation:PbCl₂(s) ⇄ Pb²⁺(aq) + 2Cl⁻(aq),
It is mentioned that the value of Ksp is 1.8 × 10⁻².
∵ The solubility product is lower for this reaction that means the ions produced are getting combined.
∴ Resulting in reducing the concentration of the ions and increasing the formation of the solid lead chloride.
So, The ions are now combining to reduce their concentrations.Answer:
The ions are now combining to reduce their concentrations.
Explanation:
Which statements describe polyatomic ions? Check all that apply.
Polyatomic ions have many charges.
Polyatomic ions have one overall charge.
Polyatomic ions repel other ions to form ionic bonds.
Polyatomic ions attract other ions to form ionic bonds.
Polyatomic ions are made up of only one type of atom.
Polyatomic ions are made up of two or more types of atoms.
Answer:
B, D, F
Explanation:
The polyatomic ion statements are
- Polyatomic ions have one overall charge.
- Polyatomic ions are made up of two or more types of atoms.
- Polyatomic ions are ions composed of two or more atoms that are covalently bonded together and carry an overall electrical charge due to the loss or gain of electrons.
- They have one overall charge because the entire molecule gains or loses electrons to become an ion.
- Polyatomic ions are composed of two or more types of atoms, usually including both nonmetals and sometimes a central metal atom.
Complete Question:
Which statements describe polyatomic ions? Check all that apply.
- Polyatomic ions have many charges.
- Polyatomic ions have one overall charge.
- Polyatomic ions repel other ions to form ionic bonds.
- Polyatomic ions attract other ions to form ionic bonds.
- Polyatomic ions are made up of only one type of atom.
- Polyatomic ions are made up of two or more types of atoms.
. Write the following isotope in nuclide notation (e.g., “ ”): copper-70
Answer:
[tex]{\boxed{\text{$_{29}^{70}${Cu}}}[/tex]
Explanation:
The atomic number (Z) of copper is 29 and this isotope has an atomic mass (A) of 70.
The general symbol for an isotope E is [tex]_{Z}^{A}\text{E}[/tex].
The atomic number is a left subscript, and the atomic mass is a left superscript.
[tex]\rm {\text{The nuclide notation for copper-70 is }}{\boxed{\textbf{$_{29}^{70}${Cu}}}[/tex]
2. Iron reacts with oxygen gas according to the following equation:
4 Fe + 3 O2 -> 2 Fe2O3
If 2 moles of oxygen gas is used in the reaction,
a) how many moles of iron, Fe, will be required?
(b) how many moles of iron(III) oxide, Fe2O3, will be produced?
3. Potassium sulfate can be prepared by the reaction between dilute sulfuric acid
and potassium carbonate.
H2SO4 + K2CO3 → K2SO4 + CO2 + H2O
Calculate the mass of potassium sulfate that can be prepared from 3.45 g of
potassium carbonate.
4. The reaction between zinc and aqueous chromium(III) nitrate can be represented
by the following equation:
3 Zn (s) + 2 Cr(NO3)3 → 3 Zn(NO3)2 + 2 Cr
If 16.25 g of zinc is used to react with chromium(III) nitrate, calculate the mass of
chromium that will be produced.
5. Ethane, CzHe, burns in oxygen gas according to the following equation:
2 C2He + 7 02 – 4 CO2 + 6H20
If 72 dm of ethane gas is completely burnt in oxygen, calculate
(a) the volume of carbon dioxide, measured at room temperature and
pressure produced.
(b) the volume of oxygen, measured at room temperature and pressure
required
Answer:
2. a) 2.67 mol.
b) 1.33 mol.
3. 4.35 g.
4. 8.67 g.
5. a) 143.86 L.
b) 251.75 L.
Explanation:
2. Iron reacts with oxygen gas according to the following equation:
4Fe + 3O₂ → 2Fe₂O₃ , If 2 moles of oxygen gas is used in the reaction,
Fe reacts with O₂ according to the balanced equation:4Fe + 3O₂ → 2Fe₂O₃,
It is clear that 4 mole of Fe react with 3 mole of O₂ to produce 2 moles of Fe₂O₃.
a) how many moles of iron, Fe, will be required?
using cross multiplication:
3 mol of O₂ require → 4 mol of Fe, from the stichiometry.
2 mol of O₂ require → ??? mol of Fe.
∴ The no. of moles of of Fe are required = (2 mol)(4mol)/(3 mol) = 2.67 mol.
(b) how many moles of iron(III) oxide, Fe₂O₃, will be produced?
using cross multiplication:
3 mol of O₂ produce → 2 mol of Fe₂O₃, from the stichiometry.
2 mol of O₂ require → ??? mol of Fe₂O₃.
∴ The no. of moles of of Fe₂O₃ are produced = (2 mol)(2 mol)/(3 mol) = 1.33 mol.
3. Potassium sulfate can be prepared by the reaction between dilute sulfuric acid and potassium carbonate.
H₂SO₄ + K₂CO₃ → K₂SO₄ + CO₂ + H₂O,
Calculate the mass of potassium sulfate that can be prepared from 3.45 g of potassium carbonate.
H₂SO₄ reacts with K₂CO₃ according to the balanced equation:H₂SO₄ + K₂CO₃ → K₂SO₄ + CO₂ + H₂O,
It is clear that 1 mole of H₂SO₄ reacts with 1 mole of K₂CO₃ to produce 1 mole of K₂SO₄, 1 mole of CO₂ and 1 mole of H₂O.
Firstly, we need to calculate the no. of moles of 3.45 g of K₂CO₃:
no. of moles of K₂CO₃ = mass/molar mass = (3.45 g)/(138.205 g/mol) = 0.025 mol.
using cross multiplication:
1 mol of K₂CO₃ produce → 1 mol of K₂SO₄, from the stichiometry.
∴ 0.025 mol of K₂CO₃ produce → 0.025 mol of K₂SO₄.
∴ The mass of K₂SO₄ are produced = (no. of moles of K₂SO₄ produced)(molar mass of K₂SO₄) = (0.025 mol)(174.259 g/mol) = 4.35 g.
4. The reaction between zinc and aqueous chromium(III) nitrate can be represented by the following equation:
3Zn(s) + 2Cr(NO₃)₃ → 3Zn(NO₃)₂ + 2Cr
If 16.25 g of zinc is used to react with chromium(III) nitrate, calculate the mass of chromium that will be produced.
Zn reacts with Cr(NO₃)₃ according to the balanced equation:3Zn(s) + 2Cr(NO₃)₃ → 3Zn(NO₃)₂ + 2Cr ,
It is clear that 3 mole of Zn reacts with 2 mole of Cr(NO₃)₃ to produce 3 mole of Zn(NO₃)₂ and 2 mole of Cr.
Firstly, we need to calculate the no. of moles of 16.25 g of Zn:
no. of moles of Zn = mass/atomic mass = (16.25 g)/(65.38 g/mol) = 0.25 mol.
using cross multiplication:
3 mol of Zn produce → 2 mol of Cr, from the stichiometry.
∴ 0.25 mol of Zn produce → ??? mol of Cr.
∴ The no. of moles of Cr are produced = (2 mol)(0.25 mol)/(3 mol) = 0.167 mol.
∴ The mass of Cr are produced = (no. of moles of Cr produced)(atomic mass of Cr) = (0.167 mol)(51.9961 g/mol) = 8.67 g.
5. Ethane, C₂H₆, burns in oxygen gas according to the following equation:
2 C₂H₆ + 7 O₂ → 4 CO₂ + 6H₂O,
If 72 dm³ of ethane gas is completely burnt in oxygen, calculate
(a) the volume of carbon dioxide, measured at room temperature and
pressure produced.
Firstly, we can calculate the no. of moles of 72 dm³ ethane at room temperature and pressure using the general law of ideal gas: PV = nRT.
where, P is the pressure of the gas in atm (P = 1.0 atm).
V is the volume of the gas in L (V = 72.0 dm³ = 72.0 L).
n is the no. of moles of the gas in mol (n = ??? mol).
R is the general gas constant (R = 0.0821 L.atm/mol.K),
T is the temperature of the gas in K (T = 298.0 K, room temperature).
∴ n of ethane = PV/RT = (1.0 atm)(72.0 L)/(0.0821 L.atm/mol.K)(298.0 K) = 2.94 mol.
So, we can calculate the no. of moles of CO₂:
using cross multiplication:
2 mol of C₂H₆ produce → 4 mol of CO₂, from the stichiometry.
∴ 2.94 mol of C₂H₆ produce → ??? mol of CO₂.
∴ The no. of moles of CO₂ are produced = (2.94 mol)(4.0 mol)/(2 mol) = 5.88 mol.
∴ The volume of moles of CO₂ are produced = nRT/P = (5.88 mol)(0.0821 L.atm/mol.K)(298.0 K)/(1.0 atm) = 143.86 L.
(b) the volume of oxygen, measured at room temperature and pressure
required.
using cross multiplication:
2 mol of C₂H₆ require → 7 mol of O₂, from the stichiometry.
∴ 2.94 mol of C₂H₆ require → ??? mol of O₂.
∴ The no. of moles of O₂ are required = (2.94 mol)(7.0 mol)/(2 mol) = 10.29 mol.
∴ The volume of moles of O₂ are produced = nRT/P = (10.29 mol)(0.0821 L.atm/mol.K)(298.0 K)/(1.0 atm) = 251.75 L.