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2 years ago

What are examples of models

1 answer:

6 0

Here are 3 main types of models are ( Physical, Mathematical, and Conceptual. Models have limitations but are useful and can be changed based on a new evidence.

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For this question, the "entropy term" refers to "-TΔS". Addition reactions are generally favorable at low temperatures because _

nata0808 [166]

Answer:

Lowering the temperature typically reduces the significance of the decrease in entropy. That makes the Gibbs Free energy of the reaction more negative. As a result, the reaction becomes more favorable overall.

Explanation:

In an addition reaction there's a decrease in the number of particles. Consider the hydrogenation of ethene as an example.

$\rm H_2C\text{=}CH_2\; (g) + H_2\; (g) \stackrel{\text{Ni}^\ast}{\to} H_3C\text{-}CH_3\; (g)$ .

When $\rm H_2$ is added to $\rm H_2C\text{=}CH_2$ (ethene) under heat and with the presence of a catalyst, $\rm H_3C\text{-}CH3$ (ethane) would be produced.

Note that on the left-hand side of the equation, there are two gaseous molecules. However, on the right-hand side there's only one gaseous molecule. That's a significant decrease in entropy. In other words, $\Delta S < 0$ .

The equation for the change in Gibbs Free Energy for a particular reaction is:

$\Delta G = \Delta H + (\underbrace{- T \, \Delta S}_{\text{entropy}\atop \text{term}})$ .

For a particular reaction, the more negative $\Delta G$ is, the more spontaneous ("favorable") the reaction would be.

Since typically $\Delta S < 0$ for addition reactions, the "entropy term" of it would be positive. That's not very helpful if the reaction needs to be favorable.

$T$ (absolute temperature) is always nonnegative. However, lowering the temperature could help bring the value of

8 0

3 years ago

This chemical reaction is unbalanced: ___Pb(NO₃)₂(aq) + ___Li₂SO₄(aq) → ____PbSO₄(s) + ____LiNO₃(aq) Which coefficient should ap

kakasveta [241]

Answer: 2

Explanation:

4 0

3 years ago

Acids will corrode most _____.<br> bases<br> liquids<br> metals<br> gases

aliya0001 [1]

Acids corrode most metals

3 0

3 years ago

Read 2 more answers

What is the chemical formula for a compound between Li and Br?

natima [27]

LiBr.

<h3>Explanation</h3>

Note that the group number in this answer refers to the new IUPAC group number, which ranges from 1 to 18. Counts from the left. Start with the first two column (group 1 and 2), go on to the transition elements (Sc, Ti, etc. in group 3 through 12), and continue with the nonmetals (group 13 through 18).

Li is a group 1 metal. As a metal, it tends to form positive ions ("cations"). Metals in group 1 and 2 are <em>main group</em> metals. The charge on main group metal ions tends to be the same as the group number of the metal. Li is in group 1. The charge on an Li ion will be +1. Formula of the Li ion will be $\text{Li}^{+}$ .

Br is a group 17 nonmetal. As a nonmetal, it tends to form negative ions ("anions"). The charge on nonmetal ions excepting for H tends to equal the group number of the nonmetal minus 18. Br is in group 17. The charge on a Br ion will be 17 - 18 = -1. Formula of the Br ion will be $\text{Br}^{-}$

All the ions in an ionic compound carry charge. However, some of the ions like $\text{Li}^+$ are positive. Others ions like $\text{Br}^{-}$ are negative. Charge on the two types of ions balance each other. As a result, the compound is <em>overall</em> neutral.

1 × (+1) + 1 × (-1) = 0. The positive charge on one $\text{Li}^{+}$ ion balances the negative charge on one $\text{Br}^{-}$ ion. The two ions would pair up at a 1:1 ratio.

The empirical formula for an ionic compound shows all the ions in the compound. Positive ions are written in front of negative ions. $\text{Li}^{+}$ is positive and $\text{Br}^{-}$ is negative. The formula shall also show the simplest ratio between the ions. For the compound between Li and Br, a 1:1 ratio will be the simplest. The "1" subscript in an empirical formula can be omitted. Hence the formula: LiBr.

5 0

3 years ago

What is the mass of 0.0150 moles of Na₂SO4 (molar mass = 142.04 g/mol)?

olga2289 [7]

Answer:

2.13 g

Explanation:

(142.04)(0.0150) = 2.13 g

4 0

2 years ago