I believe the correct answers from the choices listed above are the second and the last option. At constant pressure, the systems 2A(g) + B(g) ---> 4C(g) and 2C(g) A(s) + B(s) ---> C(g) produces work to the surroundings. <span>When a gas is evolved during a chemical reaction, the gas can be imagined as displacing the atmosphere - pushing it back against the atmospheric pressure. The work done is therefore V*P where V is the volume of gas evolved, and P is the atmospheric pressure. </span>
Answer:

Explanation:
You can convert the <em>density</em> into <em>atomic density</em> using the <em>atomic weight </em>and Avogadro's number
A dimensional analysis is very helpful:

Follow the chain: g cancels with g, mol cancels with mol; at the end, what remains is atoms/cm³, which is what you want.
Use that with your data:

Answer:
There is one nitrate ion in the products, and two in the reactants of this equation.
Explanation:
1: We know a nitrate ion has the formula
, so we just need to count how many of them are on each side of the equation.
2: To find how many are in the reactants of the equation, you look at the left hand side (before the arrow). You can see the section
, which shows that there are two nitrate ions in the reactant side (as seen by the little 2).
3: To find how many are on the products side, you do the same thing - this time there is only one
in the lithium nitrate.
So, there is one nitrate ion in the products, and two in the reactants of this equation.
Answer:
We need 4.28 grams of sodium formate
Explanation:
<u>Step 1:</u> Data given
MW of sodium formate = 68.01 g/mol
Volume of 0.42 mol/L formic acid = 150 mL = 0.150 L
pH = 3.74
Ka = 0.00018
<u>Step 2:</u> Calculate [base)
3.74 = -log(0.00018) + log [base]/[acid]
0 = log [base]/[acid]
0 = log [base] / 0.42
10^0 = 1 = [base]/0.42 M
[base] = 0.42 M
<u>Step 3:</u> Calculate moles of sodium formate:
Moles sodium formate = molarity * volume
Moles of sodium formate = 0.42 M * 0.150 L = 0.063 moles
<u>Step 4:</u> Calculate mass of sodium formate:
Mass sodium formate = moles sodium formate * Molar mass sodium formate
Mass sodium formate = 0.063 mol * 68.01 g/mol
Mass sodium formate = 4.28 grams
We need 4.28 grams of sodium formate
Answer:

Explanation:
We are asked to find how much heat a sample of water absorbed. Since we are given the mass, temperature, and specific heat, we will use the following formula.

The mass (m) of the sample is 112.5 grams. The specific heat capacity of water (c) is 4.184 Joules per gram degree Celsius. The difference in temperature (ΔT) is found by subtracting the initial temperature from the final temperature.
- ΔT= final temperature - initial temperature
The water was heated from 12.5 degrees Celsius to 92.1 degrees Celsius.
- ΔT= 92.1 °C - 12.5 °C= 79.6°C
Now we know three variables and can substitute them into the formula,
- m= 112.5 g
- c= 4.184 J/g °C
- ΔT= 79.6 °C

Multiply the first 2 numbers. Note the units of grams cancel.



Multiply again. This time the units of degrees Celsius cancel.



37, 467.72 Joules of heat are absorbed by the sample fo water.