Can someone check that I did this correctly? What does it mean by “networks” and “formula units”?

9 x 1025 m How many significant figures are in this measurement?

sattari [20]

Answer: 9000 - 1 significant figure

Explanation: Since you are multiplying, the number with the least amount of significant figures determines the number of significant figures in the answer. The number 9 has 1 significant figure and 1025 and has 4 significant figures so 9 has the fewest significant figures, meaning your answer will be 1 significant figure.

8 0

3 years ago

Please help last assignment of the day

Andrej [43]

In this qn, you use the mole formula,

amount (mol) = mass (g) ÷ molar mass

(molar mass is the mass number of an element, which u can find by referring to the periodic table)

so by subbing in the values given to you, you can find the answer

5. amount of Cu = 55.9 ÷ 63.5 = 0.880mol (3sf)

6. amount of N2 = 340 ÷ 2(14.0) = 12.1mol (3sf)

(note: you multiply the molar mass of N by 2 as there are 2 N atoms)

for qn 7 and 8, youre finding the mass and not the amount. By bringing the molar mass over to the other side of the formula, you get

mass = amount (mol) × molar mass

thus,

7. mass of Fe = 0.063 × 55.8 = 3.52g (3sf)

8. mass of H2 = 94.7 × 2(1.0) = 47.4g (3sf)

extra things to take note of:

- likewise, you can also find the molar mass of an element by using

molar mass = mass(g) ÷ amount(mol)

^^ this is commonly only needed when you need to find the molar mass of an isotope. the question will give you the amount and mass of the element, and you just need to factor them in to find your answer.

- typically, you use 3 sf in your final answer and 5sf in your working. remember to write (3sf) at the end of your number statement when necessary.

- when you get an answer of (eg.) 0.6mol, you still need to write it in 3sf, so your answer would be 0.600mol

3 0

3 years ago

How cholestrol transport fatty acids in body ?

sleet_krkn [62]

In order to use the energy stored in fat, the body breaks dow triglycerides into fatty acids, which individual cells burn for energy

4 0

3 years ago

how does increasing concentration/ temperature/ surface area affect the yield of products in a chemical reaction (not reversible

egoroff_w [7]

Answer:
Increasing concentration, temperature and surface area will increase the yield of products.

Explanation:
Concentration:
Increase in concentration of reactants will increase the number of reactants per unit volume. Therefore, the probability of collisions will increase hence, it will result in the increase in yield.

Temperature:
Increase in temperature increases the kinetic energy of reactants. Therefore, the increase in velocity of reactants results in the collisions with high energy. It makes it feasible for reactants to attain the optimum energy (activation energy) to convert into products with good yield.

Surface Area:
The reactants in grinded / powder form reacts fast as compared to solid form. In fact, grinding results in increase of the surface area of reactants. Greater surface area increases the probability of reactants to colloid. Hence, increases the yield.

6 0

3 years ago

The sodium isotope with 13 neutrons. Express your answer as an isotope

wariber [46]

Answer:

$\large\boxed{\large\boxed{^{24}_{11}Na}}$

Explanation:

The question is asking to write the isotopic symbol of the form $^A_ZX$ for the sodium isotope with 13 neutrons.

In general, the isotopic symbol in the given form shows:

The element's chemical symbol: X

A: mass number of the isotope, written as a superscript to the left of the element's simbol, and

A = number of protons + number of neutrons

Z: atomic number of the isotope, written as a subscript to the left of the elements's symbol,

Z = number of protons

The atomic symbol of sodium is Na.

The atomic number, or number of protons, is the same for every isotope of the element, and you can find it in any periodic table. Tha atomic number of sodium is 11. Thus:

Z = 11

The mass number is the number of protons plus neutrons, hence:

A = 11 + 13 = 24

Now you can write the isotope symbol for the sodium isotope with 13 neutrons:

$^{24}_{11}Na$

6 0

4 years ago