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nata0808 [166]
2 years ago
9

Which condition would have resulted from the functions of prokaryotes on early Earth?

Chemistry
1 answer:
Nitella [24]2 years ago
6 0
The 1 one and the last one
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A sample of water is heated from 60.0 °C to 75.0°C by the addition of 140 j of
kupik [55]

Mass of the water : 2.23 g

<h3>Furter explanation</h3>

Heat

Q = m.c.Δt

m= mass, g

c = heat capacity, for water : 4.18 J/g° C.

ΔT = temperature

Q= 140 J

Δt = 75 - 60 = 15

mass of the water :

\tt m=\dfrac{Q}{c.\Delta T}=\dfrac{140}{4.18\times 15}=2.23~g

5 0
2 years ago
15 mL of acid 2 M was added to 20 mL of base 2 M into a calorimeter at room temperature (24 oC). The reaction mixture reached a
erik [133]

Answer:

here:

Explanation:

The changes in temperature caused by a reaction, combined with the values of the specific heat and the mass of the reacting system, makes it possible to determine the heat of reaction.

Heat energy can be measured by observing how the temperature of a known mass of water (or other substance) changes when heat is added or removed. This is basically how most heats of reaction are determined. The reaction is carried out in some insulated container, where the heat absorbed or evolved by the reaction causes the temperature of the contents to change. This temperature change is measured and the amount of heat that caused the change is calculated by multiplying the temperature change by the heat capacity of the system.

The apparatus used to measure the temperature change for a reacting system is called a calorimeter (that is, a calorie meter). The science of using such a device and the data obtained with it is called calorimetry. The design of a calorimeter is not standard and different calorimeters are used for the amount of precision required. One very simple design used in many general chemistry labs is the styrofoam "coffee cup" calorimeter, which usually consists of two nested styrofoam cups.

When a reaction occurs at constant pressure inside a Styrofoam coffee-cup calorimeter, the enthalpy change involves heat, and little heat is lost to the lab (or gained from it). If the reaction evolves heat, for example, very nearly all of it stays inside the calorimeter, the amount of heat absorbed or evolved by the reaction is calculated.

8 0
2 years ago
Calculate the concentration of formate in a 100mm solution of formic acid at ph 4.15. The pka for formic acid is 3.75
MissTica

The molarity of formic acid is 100 mM or 100\times 10^{-3}M. The dissociation reaction of formic acid is as follows:

HCOOH\leftrightharpoons HCOO^{-}+H^{+}

The expression for dissociation constant of the reaction will be:

K_{a}=\frac{[HCOO^{-}][H^{+}]}{[HCOOH]}

Rearranging,

[HCOO^{-}]=\frac{K_{a}[HCOOH]}{[H^{+}]}

Here, pH of solution is 4.15 thus, concentration of hydrogen ion will be:

[H^{+}]=10^{-pH}=10^{-4.15}=7.08\times 10^{-5}M

Similarly, pK_{a}=3.75 thus,

[K_{a}=10^{-pK_{a}}=10^{-3.75}=1.78\times 10^{-4}M

Putting the values,

[HCOO^{-}]=\frac{(1.78\times 10^{-4}M)(100\times 10^{-3}M)}{(7.08\times 10^{-5}M}=0.2511 M

Therefore, the concentration of formate will be 0.2511 M.

4 0
3 years ago
What is an ionic bond? A. the attraction positive ions have for free electrons B. the force that holds the valence electrons to
Olin [163]
Ionic bond is a type of chemical bond that refers to the bonding of <span>oppositely charged ions (anions and cations) because of attraction and the </span>transfer of valence electron(s) between atoms. Cation is the metal that loses electrons and become a positively charged cation, and anions are the nonmetal that accepts those electrons to become a negatively charged anion.
According this explanation, an ionic bond is:
B. the force that holds the valence electrons to the atom


6 0
3 years ago
A sample of sandstone consists of only silica (SiO2) and calcite (CaCO3). When sandstone is heated, calcium carbonate decomposes
anzhelika [568]

Answer:

0

Explanation:

To calculate, the mass of Carbondioxide is 3.45mg

Then the decomposition of Carbondioxide gives 0 on calculation

5 0
3 years ago
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