Answer:
1. Potassium, K.
2. Calcium, Ca.
3. Gallium, Ga.
4. Carbon, C.
5. Bromine, Br.
6. Barium, Ba.
7. Silicon, Si.
8. Gold, Au.
Explanation:
Atomic radius can be defined as a measure of the size (distance) of the atom of a chemical element such as hydrogen, oxygen, carbon, nitrogen etc, typically from the nucleus to the valence electrons. The atomic radius of a chemical element decreases across the periodic table, typically from alkali metals (group one elements such as hydrogen, lithium and sodium) to noble gases (group eight elements such as argon, helium and neon). Also, the atomic radius of a chemical element increases down each group of the periodic table, typically from top to bottom (column).
Additionally, the unit of measurement of the atomic radius of chemical elements is picometers (1 pm = 10 - 12 m).
1. Li or K: the atomic radius of lithium is 167 pm while that of potassium is 243 pm.
2. Ca or Ni: the atomic radius of calcium is 194 pm while that of nickel is 149 pm.
3. Ga or B: the atomic radius of gallium is 136 pm while that of boron is 87 pm.
4. O or C: the atomic radius of oxygen is 48 pm while that of carbon is 67 pm.
5. Cl or Br: the atomic radius of chlorine is 79 pm while that of bromine is 94 pm.
6. Be or Ba: the atomic radius of berryllium is 112 pm while that of barium is 253 pm.
7. Si or S: the atomic radius of silicon is 111 pm while that of sulphur is 88 pm.
8. Fe or Au: the atomic radius of iron is 156 pm while that of gold is 174 pm.
Answer:
b. reactant molecules collide more frequently and with greater energy per collision
Explanation:
As the temperature of a reaction is increased, the rate of the reaction increases because the reactant molecules collide more frequently and with greater energy per collision. When temperature is increased there is an increase in the kinetic energy of the molecules. The more the molecules move the more they collide. According to the collision theory there should be enough energy to allow bonds to be formed during a chemical reaction hence the need for greater energy per collision. Also the rate of reaction is directly proportional to the number of collisions that occur.
Answer:
38.8 mL
Explanation:
2CO(g) + O₂(g)⟶2CO₂(g)
Because pressure and temperature remain constant, we can <em>think of the moles ratios as volume ratios</em>. This means that 2mL of CO react with 1 mL of O₂ to produce 2 mL of CO₂.
Because the problem asks us to calculate the amount of oxygen gas unreacted, then CO is the limiting reactant. We <u>calculate the amount of O₂ that reacted</u>, from the available amount of CO:
82.4 mL CO * 
= 41.2 mL O₂
Thus, the oxygen gas remaining is:
80.0 mL - 41.2 mL = 38.8 mL O₂
<u>Answer:</u>
<u>For a):</u> The mass percent of naphthalene in the original sample is 31.00 %.
<u>For b):</u> The mass percent of 3-nitroaniline in the original sample is 32.03 %.
<u>For c):</u> The mass percent of benzoic acid in the original sample is 29.97 %.
<u>For d):</u> The total percent recovered is 93.00 %.
<u>Explanation:</u>
Percentage by mass is defined as the ratio of the mass of a substance to the mass of the solution multiplied by 100. The formula used for this is:
......(1)
a):
Mass of naphthalene = 0.483 g
Mass of the sample = 1.558 g
Plugging values in equation 1:
b):
Mass of 3-nitroaniline = 0.499 g
Mass of the sample = 1.558 g
Plugging values in equation 1:
c):
Mass of benzoic acid = 0.467 g
Mass of the sample = 1.558 g
Plugging values in equation 1:
d):
Total mass recovered = [0.483 + 0.499 + 0.467] = 1.449 g
Mass of the sample = 1.558 g
Plugging values in equation 1:
Answer:
D
Explanation:
In considering the half cell reactions in electrochemical cells, we consider the standard electrode potential of the two half cells. The more negative electrode potential will be the anode and the less negative electrode potential will be the cathode. The electrode potentials of Ni2+(aq)/Ni(s) is -0.25V while that of Zn2+(aq)/Zn(s) is -0.76.
Hence the selected option is the cathodic half reaction equation
