Which statements about exothermic and endothermic reactions are correct? (its a multiple choice question)
1 During an exothermic reaction, heat is given out.
2 The temperature of an endothermic reaction goes up because heat is taken in.
3 Burning methane in the air is an exothermic reaction.
A) 1.2 and 3
B) 1 and 2 only
C) 1 and 3 only
D) 2 and 3 only
Answer:
C)1 and 3 only☺️
Explanation:
What change would you expect on the rate of the SN2 reaction of 1-iodo-2-methylbutane with cyanide ion if the nucleophile concentration is halved and the alkyl halide concentration is doubled
Answer:
The rate of reaction remains the same, no change is observed
Explanation:
Remember that for an SN2 reaction, the rate of reaction depends both on the concentration of the alkyl halide and the concentration of the nucleophile.
Hence we can write; Rate = k [Alkyl halide][NaI]
This implies that if we half the concentration of the nucleophile and double the concentration of the alkyl halide, the rate of reaction just remains the same since the reaction is bimolecular and first order in both alkyl halide and nucleophile
75 g of a metal is heated to a temperature of 99C. The metal is then placed in a calorimeter containing 145 g of water at a temperature of 25C. The temperature of the water in the calorimeter increase to a final temperature of 28C. What is the specific heat of the metal?
Answer:
0.34 J / g ⁰C
Explanation:
Let the specific heat of metal be s .
heat will be lost by hot metal and gained by water .
heat lost by metal = mass x specific heat x loss of temperature
= 75 x s x ( 99 - 28 ) = 5325 s
heat gained by water = mass x specific heat x gain of temperature
= 145 x 4.18 x ( 28 - 25 ) = 1818.3
heat lost = heat gained
5325 s = 1818.3
s = 0.34 J / g ⁰C
the gram formula mass of NH4Br is what (please provide explanation, thank you)
Answer:
97.95 g/mol
Explanation:
Step 1: Define molar masses
Molar Mass of N - 14.01 g/mol
Molar Mass of H - 1.01 g/mol
Molar Mass of Br - 79.90 g/mol
Step 2: Find amounts of molar masses
1 mol N - 14.01 g/mol
4 mol H - 4.04 g/mol
1 mol Br - 79.90 g/mol
Step 3: Find molar mass of compound
Molar Mass N + 4 Molar Mass H + 1 Molar Mass Br
14.01 g/mol + 4.04 g/mol + 79.90 g/mol
97.95 g/mol
WILL MARK BRAINLIEST please
Answer:
C is the only reasonable answer.. but this is 6th grade science and I'm in 7th, so I'm pretty sure I'm right
Chemistry pick two answers
A dog has a mass of 19 kg. What is the mass of the dog in grams,expressed in scientific notation
Answer: 1.9 x 10^4
Explanation:
A dog has a mass of 19 kg. The mass of the dog in grams, expressed in scientific notation, is 1.95 × 10⁴ g.
What is mass?Mass is the quantity of matter in a physical body. The product of the compound's molar mass and the substance's moles are defined as mass.
Measuring units to determine the size, weight, or quantity of any object. Seven fundamental measurement units are utilized in daily life and across the globe.
These units of measurement are the meter, which is used to measure distance, and the second, which is used to measure. Grams and kilograms are the measuring units that are used to measure the quantity of a solid item.
The mass of the dog in grams is:
1 kilogram = 1000 grams
19.5 kg × (10³ g/1 kg) = 1.95 × 10⁴ g.
Thus, the mass of the dog in grams is 1.95 × 10⁴ g.
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Why does a small pebble sink in water?
A small pebble sinks in water because its density is greater than the density of water. Density is a measure of how much mass is packed into a given volume. If an object is denser than the liquid it is placed in, it will sink.
When a pebble is dropped into water, the water exerts an upward force called buoyancy. This force opposes the weight of the pebble, and if the pebble is less dense than water, it will experience an upward force greater than its weight and float.
However, if the pebble's density is greater than that of water, the downward force due to its weight will be greater than the upward buoyant force, causing it to sink.
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While looking at calcium (Ca) on the periodic table, a student needs to find an element with a greater atomic mass in
the same period. Where should the student look?
O directly up
O directly down
O directly to the left
O directly to the right
Answer:
D. Directly to The Right
Can someone please help?
Answer:
On Question 3
Explanation:
try using any type or liquid like water, milk, soda, juice, coffee, tea, beer, or wine or any type and use the following questions by using a measuring cup from the kitchen tooling shelf. Use that to answer the question and see if that helps. your welcome btw
Help asap!!!!
What are elements in the tall columns of the periodic table called?
A. Representative elements
B. Valence elements
C. Atomic elements
D. Period elements
The elements in the tall columns of the periodic table are called representative elements or main group elements. They exhibit similar chemical properties within their respective groups due to their shared number of valence electrons. The terms "valence elements," "atomic elements," and "period elements" are not commonly used or recognized in the context of the periodic table.
The correct answer is option A.
The elements in the tall columns of the periodic table are called "A. Representative elements," also known as the "main group elements" or "group A elements." These elements are found in groups 1, 2, and 13 to 18 (excluding the transition metals) on the periodic table.
Representative elements are characterized by having similar chemical properties within their respective groups. This similarity arises from the fact that elements within the same group have the same number of valence electrons, which are the electrons in the outermost energy level of an atom. Valence electrons play a crucial role in determining the chemical behavior and reactivity of an element.
The representative elements include the alkali metals (Group 1), alkaline earth metals (Group 2), boron group (Group 13), carbon group (Group 14), nitrogen group (Group 15), oxygen group (Group 16), halogens (Group 17), and noble gases (Group 18). These elements exhibit a wide range of properties, from highly reactive metals to nonmetals and inert gases.
The term "valence elements" mentioned in option B is not commonly used in the context of the periodic table. Valence electrons are indeed significant in determining chemical properties, but they are not specific to the elements in the tall columns. Valence electrons are found in elements across the periodic table.
"Atomic elements" mentioned in option C is a vague term and does not specifically refer to the elements in the tall columns. All elements on the periodic table are atomic in nature, as they are composed of atoms.
"Period elements" mentioned in option D is not a recognized term in the context of the periodic table.
In conclusion, the elements in the tall columns of the periodic table are known as representative elements or main group elements. These elements exhibit similar chemical properties within their respective groups due to their shared number of valence electrons.
Therefore, from the options provided the correct one is A.
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Give an example of experimental bias
Answer:
chongus because he's the only good one
how much valence electrons does aluminum have
Answer:
3
Explanation:
It is in the third column or group on the periodic table
If you've ever shifted realities, How long did it take you?
Answer:
2 days.
Explanation:
A chemist is asked to determine the specific heat capacity of an unknown mineral. The 149-g sample was heated to 92.7°C and placed into a calorimeter containing 81.4 g of water at 20.0°C. The heat capacity of the calorimeter was 12.8 J/K. The final temperature in the calorimeter was 23.7°C. What is the specific heat capacity (in J/g°C) of the mineral? Enter to 4 decimal places.
Answer:
The specific heat of the mineral is 0.1272J/g°C
Explanation:
The sample is given energy to the calorimeter and the sample of water.
The energy released for the sample is equal to the energy absorbed for both the calorimeter and the water:
C(Sample)*m*ΔT = C(Calorimeter)*ΔT + C(water)*m*ΔT
Where C is specific heat
m is mass of the sample and water
And ΔT is change in temperature
C(Sample)*149g*(92.7°C-23.7°C) = 12.8J/K*(23.7°C-20.0°C) + 4.184J/g°C*81.4g*(23.7°C-20.0°C)
C(Sample)*10281g°C = 47.36J + 1260.1J
C(Sample) = 0.1272J/g°C
The specific heat of the mineral is 0.1272J/g°C
The specific heat of the mineral is 0.1272J/g°C
Calculation of the specific heat:
The energy released for the sample should be equivalent to the energy absorbed for both the calorimeter and the water:
So,
C(Sample)*m*ΔT = C(Calorimeter)*ΔT + C(water)*m*ΔT
here C is specific heat
m is mass of the sample and water
And ΔT is change in temperature
Now
C(Sample)*149g*(92.7°C-23.7°C) = 12.8J/K*(23.7°C-20.0°C) + 4.184J/g°C*81.4g*(23.7°C-20.0°C)
C(Sample)*10281g°C = 47.36J + 1260.1J
C(Sample) = 0.1272J/g°C
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2.3 grams of sodium reacts with water and 0.080 grams of hydrogen has been collected what are the theoretical and percent yields of hydrogen gas?
Answer:
Theoretical yield = 0.1 g
Percent yield = 80%
Explanation:
Given data:
Mass of sodium = 2.3 g
Actual yield of hydrogen = 0.080 g
Theoretical yield = ?
Percent yield = ?
Solution:
Chemical equation:
2Na + 2H₂O → H₂ + 2NaOH
Number of moles of sodium:
Number of moles = mass/ molar mass
Number of moles = 2.3 g/ 23 g/mol
Number of moles = 0.1 mol
Now we will compare the moles of sodium with hydrogen to calculate the theoretical yield.
Na : H₂
2 : 1
0.1 : 1/2×0.1 = 0.05 mol
Mass of hydrogen produced:
Mass = number of moles × molar mass
Mass = 0.05 mol × 2 g/mol
Mass = 0.1 g
Percent yield of hydrogen:
Percent yield = actual yield / theoretical yield ×100
Percent yield = 0.08 g/ 0.1 g×100
Percent yield = 0.8×100
Percent yield = 80%
According to the law of superposition, where would you find objects with an older relative age?
Answer:
The law of superposition states that each rock layer is older than the one above it. So, the relative age of the rock or fossil in the rock is older if it is farther down in the rock layers.
Lead(II) nitrate and ammonium iodide react to form lead(II) iodide and ammonium nitrate according to the reaction
Answer:
1.186L or 1186mL.
Explanation:
The volume of a 0.290 m NH4I solution that is required to react with 253 ml of a 0.680 m Pb(NO3)2 solution is 1.186 liters or 1186 ml.
A hawk swoops down and catches a squirrel. The squirrel provides energy for the hawk. What happens to the rest of the matter?
Answer:
The rest of the food molecule is converted to other carbon molecules. The hawk cannot consume all the parts of the squirrel. It will feed as a carnivore on the fleshy part of its prey. The matter is converted to other carbon molecules
Explanation:
Galium is a metal that can melt in your hand at 302.93 k. what is the temperature in celcius ?
Explanation:
subtract it into 273.15to convert it in to celcius
How is the periodic table generally arranged?
Answer:
It is generally arranged by the atomic number
Explanation:
Which element requires the least amount of energy to remove the most loosely held electron from a gaseous atom in the ground state? 1. K 2. Kr 3. As 4.br
Answer:
K
Explanation:
How many protons does Lithium have?
Answer:
3 ................................
Answer: 3
Explanation:
yes
Why is the primary standard, KHP, used in the determination of the molar mass of an acid?
Potassium acid phthalate will serve as our primary standard. This is a large molecule (KHC8H4O4) with a molar mass of 204.2 g/mol. Instead of writing the whole formula, we abbreviate it as KHP, where "P" stands for the phthalate ion, C8H4O42-, not for phosphorus. KHP is an acidic substance, with the ionizing hydrogen being set forward in the formula for emphasis. Therefore, KHP is monoprotic and will react with NaOH in a simple 1 to 1 relationship according to the following equation:
8 is subtracted from the square of a number.
Answer:
how do I answer without context
Given that one mole occupies 22.4 L at STP, show that R = .082 (atm * L)/(mol*K)
Mass of a proton =...........
Answer:
Explanation:
A proton has a mass of approximately 938 MeV/c2, of which the rest mass of its three valence quarks contributes only about 9.4 MeV/c2; much of the remainder can be attributed to the gluons' QCBE.
Which properties do not change the composition of a substance?
neither chemical nor physical properties
physical properties
chemical properties
chemical and physical properties
Answer:
Physical Properties
Explanation:
PHYSICAL PROPERTY
Answer:
phycical propertys
Explanation:
jut took the test got it right
A ___ reaction takes two or more reactants to make one product
Answer:
Synthesis
Explanation:
A sysnthesis reaction takes two or more reactants to create one product
please help me :( What is the correct ratio of carbon to hydrogen to oxygen in glucose (C6H120.)?
12:12:6
01:2:1
02:1:1
6:6:12
Answer:
Either 12:12:6 or 6:6:12
Explanation:
If I remember correctly the answer should be 6:6:12