Which of the following best describes an atom?

All chemical reactions convert one substance into another. select one:<br> a. true.<br> b. false.

seropon [69]

B. false

All reactions have an equilibrium, at which the rate of the reaction rates on each side of the equation are equal to each other. Sometimes that can be one-way, but it’s more often a two-way street. Where you’ll have an amount of products and reactants.

6 0

3 years ago

Consider the following unbalanced half-reaction:

Aleks [24]

Answer: B

Hope this helped :)

3 0

3 years ago

A coffee-cup calorimeter contains 140.0 g of water at 25.1°C . A 124.0-g block of copper metal is heated to 100.4°C by putting i

Kisachek [45]

Answer:

(a) 3347 J; (b) 3043 J; (c) 58 J/K; (d) 35.5 °C

Explanation:

(a) Heat lost by copper

The formula for the heat lost or gained by a substance is

q =mCΔT

ΔT = T₂ - T₁= 30.3 °C - 100.4 °C = -70.1 °C = -70.1 K

q = 124.0 g × 0.385 J·K⁻¹g⁻¹ × (-70.1 K) = -3347 J

The negative sign shows that heat is lost.

The copper block has lost 3347 J.

(b) Heat gained by water

ΔT = 30.3 °C - 25.1 °C = 5.2 °C = 5.2 K

q = 140.0 g × 4.18 J·K⁻¹g⁻¹ × 5.2 K = 3043 J

The water has gained 3043 J.

(c) Heat capacity of calorimeter

Heat lost by Cu = heat gained by water + heat gained by calorimeter

The temperature change for the calorimeter is the same as that for the water.

ΔT = 5.2 K

$\begin{array}{rcl}\text{3347 J} & = & \text{3043 J} + C \times \text{5.2 K}\\\text{304 J} & = & 5.2C \text{ K}\\C & = & \dfrac{\text{304 J}}{\text{5.2 K}}\\\\& = & \text{58 J/K}\\\end{array}$

The heat capacity of the calorimeter is 58 J/K.

(d) Final temperature of water

$\begin{array}{rcl}\text{Heat lost by copper } + \text{Heat gained by water}& = &0 \\\text{Heat lost by copper}& = &-\text{Heat gained by water} \\m_{\text{Cu}}C_{\text{Cu}}\Delta T_{\text{Cu}}& = & -m_{\text{w}}C_{\text{w}}\Delta T_{\text{w}}\\\end{array}\\$

$\begin{array}{rcl}\text{124.0 g} \times \text{0.385 J$\cdot$K$^{-1}$g$^{-1}$}\times \Delta T_{\text{Cu}}& = & -\text{140.0 g} \times 4.18 \text{ J$\cdot$ K$^{-1}$g$^{-1}$}\times \Delta T_{\text{w}}\\\text{47.7 J$\cdot$K$^{-1}$}\times \Delta T_{\text{Cu}}& = &-\text{585 J$\cdot$ K$^{-1}$g}\times \Delta T_{\text{w}}\\\Delta T_{\text{Cu}} & = & -12.26\Delta T_{\text{w}}\\\end{array}$

$\begin{array}{rcl}\Delta T_{\text{f}} - 100.4 \, ^{\circ}\text{C} & = & -12.26(\Delta T_{\text{f}} - 30.3\, ^{\circ}\text{C})\\\Delta T_{\text{f}} - 100.4 \, ^{\circ}\text{C} & = & -12.26\Delta T_{\text{f}} + 371\, ^{\circ}\text{C}\\13.26\Delta T_{\text{f}} & = & 471\, ^{\circ}\text{C}\\\Delta T_{\text{f}} & = & 35.5\, ^{\circ}\text{C}\\\end{array}$

The final temperature of the water would be 35.5 °C.

7 0

3 years ago

Circle the letter of each sentence that is part of John Dalton’s atomic theory.

satela [25.4K]

Answer:

A) All the elements are composed of atoms.

d) Atoms cannot be created or destroyed in any chemical changes.

c) An atom of one element cannot be changed into an atom of a different element.

Explanation:

The main postulates of Dalton atomic theory was:

1) The matter is composed of atoms and atom is indivisible particle which can not be destroyed.

2) The atoms of an element are identical.

3) The atoms of different elements are combining with definite proportion and form compounds.

4) The atoms of different elements are different from each other.

5) During chemical reaction rearrangement of atoms occur and form new compounds.

4 0

3 years ago

The oxidation of an unsaturated fatty acid leads to the production of fewer ATPs than a saturated fatty acid with the same numbe

kirill [66]

Answer:

C) the double bond results in the bypassing of the first oxidation step of the pathway, thereby eliminating one FADH2 product

Explanation:

The beta oxidation of fatty acids is the process by which long chain saturated and unsaturated fatty acids are oxidized to the two-carbon product, acetylCoA.

The beta oxudation of fatty acids occurs in four steps after which the chain length is shortened by 2 with cleavage of an acetylCoA molecule.

The first step involves the oxidation of the fatty acid with introduction of a double bond between C-2 and C-3 of the long carbon chain. This reaction produces FADH2 which donates its electrons to electron carriers in the electron transport chain tomproduce 1.5 moles of ATP. This is the case with saturated fatty acids.

However, in unsaturated fatty acids (which are less reduced than saturated fatty acids) where there is already a double bond innthe molecule, the double bond results in the bypassing of the first oxidation step of the pathway, thereby eliminating one FADH2 product.

This causes a reduction In the number of ATP produced by unsaturated fatty acids when compared to saturated fatty acids.

8 0

3 years ago