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uranmaximum [27]

2 years ago

15

Identify at least three control variables that could be used with this investigation: What temperature allows for bacterial grow

th to occur quickly?

2 answers:

Olenka [21]2 years ago

7 0

Answer:

whats the expirement

Explanation:

Over [174]2 years ago

6 0

Answer:

Time allowed for incubation, size of the dish, the amount of light, amount of agar, the type of agar…etc

Explanation:

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Microwaves are used to heat food in microwave ovens. The microwave radiation is absorbed by moisture in the food. This absorptio

DanielleElmas [232]

efw lol ewd sa dada

5 0

2 years ago

Name 3 objects found in the Milky Way galaxy.

dolphi86 [110]

Answer:

The Earth, Stars, and Mars I guess...

5 0

2 years ago

A 3.42 gram sample of an unknown gas is found to occupy a volume of 1.90 L at a pressure of 547 mm Hg and a temperature of 33 °C

liq [111]

Use the Ideal Gas Law to find the moles of gas first.

Be sure to convert T from Celsius to Kelvin by adding 273.

Also I prefer to deal with pressure in atm rather than mmHg, so divide the pressure by 760 to get it in atm.

PV = nRT —> n = PV/RT
P = 547 mmHg = 547/760 atm = 0.720 atm
V = 1.90 L
T = 33°C = 33 + 273 K = 306 K
R = 0.08206 L atm / mol K

n = (0.720 atm)(1.90 L) / (0.08206 L atm / mol K)(306 K) = 0.0545 mol of gas

Now divide grams by mol to get the molecular weight.

3.42 g / 0.0545 mol = 62.8 g/mol

3 0

2 years ago

Anything in red is the question

laila [671]

Answer:

Question 19: the three are molecular compounds.

Question 20: CuSO₄.5H₂O

Explanation:

<em>Question 19.</em>

C₂H₄

HF

H₂O₂

All of them are the combination of two kinds of different atoms in fixed proportions.

C₂H₄: two carbon atoms per four hydrogen atoms

HF: one hydrogen atom per one fluorine atom

H₂O₂: two hydrogen atoms per two oxygent atoms

Thus, they all meet the definition of compund: a pure substance formed by two or more different elements with a definite composition.

Molecular compounds are formed by covalent bonds and ionic compounds are formed by ionic bonds.

Two non-metal elements, like H-F, C - C, C - H, H-O, H - H, and O - O will share electrons forming covalent bonds to complete their valence shell. Thus, the three compounds are molecular and not ionic.

<em>Question 20. </em>Formula of copper(II) sulfate hydrate with 36.0% water.

Copper(II) sulfate is CuSO₄. Its molar mass is 159.609g/mol

Water is H₂O. Its molar mass is 18.015g/mol

Calling x the number of water molecules in the hydrate, the percentage of water is:

$\dfrac{18.015x}{18.015x+159.609}=36\%\\ \\ \\ \dfrac{18.015x}{18.015x+159.609}=0.36$

From which we can solve for x:

$18.015x=6.4854x+57.45924\\ \\ 11.5296x=57.45924\\ \\ x\approx4.98\approx5$

Thus, there are 5 molecules of water per each unit of CuSO₄, and the formula is:

CuSO₄.5H₂O

4 0

2 years ago

A chemist adds 485 mL of a 0.0025 mol/L calcium sulfate solution to a reaction flask. Calculate the mass in grams of calcium sul

viva [34]

Answer : The mass in grams of calcium sulfate is 0.16 grams.

Explanation :

Molarity : It is defined as the number of moles of solute present in one litre of solution.

Formula used :

$Molarity=\frac{\text{Mass of solute}\times 1000}{\text{Molar mass of solute}\times \text{Volume of solution}}$

Solute is, $CaSO_4$

Given:

Molarity of $CaSO_4$ = 0.0025 mol/L

Molar mass of $CaSO_4$ = 136 g/mole

Volume of solution = 485 mL

Now put all the given values in the above formula, we get:

$0.0025=\frac{\text{Mass of }CaSO_4\times 1000}{136\times 485}$

$\text{Mass of }CaSO_4=0.16g$

Thus, the mass in grams of calcium sulfate is 0.16 grams.

6 0

2 years ago