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4 years ago

TUESDAY:

Chemistry

2 answers:

puteri [66]4 years ago

7 0

Answer:

Protons=positive

Electrons=negative

Neutrons=Neutral

Explanation:

I am pretty sure this is what you are asking for if not just tell me

Rzqust [24]4 years ago

5 0

Protons are positive
Neutrons are neutral
Electrons are negatively charged

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Which of these is not a commonly mined metallic substance?

Sliva [168]

Answer:

C) quartz

Explanation:

Quartz is a common mineral. Also, quartz isn't a metallic substance. I'm hoping that this helps :)

5 0

3 years ago

1. 7.85 g of sodium metal is added to 200 mL of 0.0450 M HNO3

kumpel [21]

Answer:

a)0.765 g

b)7.613 g

c)0.20 L

Explanation:

Consider the reaction involved;

Na(s) + HNO3(aq) ----> NaNO3(s) + H2(g)

Note that, if a hot, saturated aqueous solution of sodium nitrate was allowed to cool, solid sodium nitrate would crystallise out of the solution and this would also be classed as a precipitate. This is the case here.

Number of moles of sodium reacted= mass of sodium reacted/ molar mass of sodium

Number of moles of sodium= 7.85g/23gmol-1

Number of moles of sodium= 0.34 moles of sodium

Number of moles of acid reacted= concentration of acid × volume of acid

Number of moles of acid= 0.0450 × 200/1000

Number of moles of acid= 9×10^-3 moles

Therefore, HNO3 is the limiting reactant.

1 mole of HNO3 yield 1 mole of NaNO3

9×10^-3 moles of HNO3 yield 9×10^-3 moles of NaNO3

Hence mass of NaNO3= number of moles × molar mass

Mass of NaNO3= 9.0×10^-3 moles × 84.9947 g/mol

Mass of NaNO3= 0.765 g of NaNO3

Since

1 mole of sodium metal reacts with 1 mole of HNO3

9×10^-3 moles of sodium reacts with 9×10^-3 moles of HNO3

Therefore amount of unreacted sodium metal = 0.34 moles - 9×10^-3 moles = 0.331 moles

Mass of unreacted sodium metal = 0.331 moles × 23 gmol-1= 7.613 g

If 1 mole of HNO3 yields 1 mole of hydrogen gas

9×10^-3 moles of HNO3 yields 9×10^-3 moles of hydrogen gas.

1 mole of hydrogen gas occupies 22.4 L

9×10^-3 moles of hydrogen gas will occupy 9×10^-3 moles × 22.4/1 = 0.20 L

3 0

3 years ago

A sample of gas has a mass of 827 mg . Its volume is 0.270 L at a temperature of 88 ∘ C and a pressure of 975 mmHg . Find its mo

avanturin [10]

Steps:

Mw = w * R * T / p * V

T = 88 + 273 => 361 K

p = 975 mmHg in atm :

1 atm = 760 mmHg

975 mmg / 760 mmHg => 1.28 atm

Therefore:

= 0.827 * 0.0821 * 361 / 1.28 * 0.270

= 24.51 / 0.3456

molar mass = 70.92 g/mol

7 0

3 years ago

A circle has a radius of 5 feet and a central angle AOB that measures 10°. What is the length of the intercepted arc AB? Use 3.1

algol [13]

We are asked to solve for the arc length of the intercepted arc and the formula is shown below:
Arc length = 2*pi*r(central angle/360°)
r = 5 feet
central angle = 10°

Solving for the arc length, we have:
Arc length = 2*3.14*5 (10/360)
Arc length = 0.872 feet

The arc length is 0.872 feet.

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3 years ago

A student is doing an experiment to determine the effects of temperature on an object. He writes down that the initial temperatu

bogdanovich [222]

Answer:

1) The Kelvin temperature cannot be negative

2) The Kelvin degree is written as K, not ºK

Explanation:

The temperature of an object can be written using different temperature scales.

The two most important scales are:

- Celsius scale: the Celsius degree is indicated with ºC. It is based on the freezing point of water (placed at 0ºC) and the boiling point of water (100ºC).

- Kelvin scale: the Kelvin is indicated with K. it is based on the concept of "absolute zero" temperature, which is the temperature at which matter stops moving, and it is placed at zero Kelvin (0 K), so this scale cannot have negative temperatures, since 0 K is the lowest possible temperature.

The expression to convert from Celsius degrees to Kelvin is:

$T(K)=T(^{\circ}C)+273.15$

Therefore in this problem, since the student reported a temperature of -3.5 ºK, the errors done are:

1) The Kelvin temperature cannot be negative

2) The Kelvin degree is written as K, not ºK

6 0

4 years ago