A chemical or physical change that releases heat into its surroundings is.....

How many grams of mgo are produced when 40.0 grams of o2 react completely with mg? 2 mg (s) + o2 (g) → 2 mgo (s)?

SSSSS [86.1K]

Answer: -

100 grams

Explanation: -

Mass of Oxygen = 40 g

Chemical formula of oxygen gas = O2

Molar mass of oxygen = 16 x 2 = 32 gram

Atomic mass of Mg = 24g

Molar mass of MgO = 24 x 1 + 16 x 1 =40 gram

The balanced chemical equation for the reaction is

2Mg + O2 -- > 2 MgO

So from the balanced equation we see that 1 O2 react to give 2 MgO

32 grams of O2 react to give 2 x 40 gram of MgO

40 grams of O2 react to give $\frac{2 x 40 gram x 40 gram}{32 gram}$

=100 gram of MgO

8 0

3 years ago

Convert 7.89 x 10^8 molecules of water to liters.

NNADVOKAT [17]

Answer:

2.94 x 10⁻¹⁴L

Explanation:

To solve this problem, we have to assume that the condition of this water is at standard temperature and pressure, STP.

At STP;

1 mole of gas have a volume of 22.4L

So, let us find the number of moles of this water first;

6.02 x 10²³ molecules can be found in 1 mole of a substance

7.89 x 10⁸ molecules will contain $\frac{7.89 x 10^{8} }{6.02 x 10^{23} }$ = 1.31 x 10⁻¹⁵mole of water

So;

Volume of water = 22.4 x 1.31 x 10⁻¹⁵ = 2.94 x 10⁻¹⁴L

5 0

3 years ago

What is the standard cell notation for a galvanic cell made with silver and nickel?

MA_775_DIABLO [31]

Answer:

Ni(s)∣∣Ni2+(aq) ∣∣∣∣ Ag+(aq)∣∣Ag(s)

Explanation:

Start by finding the standard reduction potential for the Ag+ and Ni2+ ion. Normally, the values are listed at the back of most chemistry textbooks.

Ag+(aq)+1e−→Ag(s) Eo=0.80 V
Ni2+(aq)+2e−→Ni(s) Eo=−0.23 V

In the galvanic cell, the reaction is spontaneous and for a spontaneous reaction Eocellmust be a positive quantity.

Eocell=EoAnode+Eocathode

Manipulate the two equations so that Eocell is positive. Note that the anode is the site of oxidation (where electrons are lost) and the cathode (where electron are gained) is the site for reduction.

Ag+(aq)+1e−→Ag(s) Eo=0.80 V
Ni(s)→Ni2+(aq)+2e− Eo=0.23 V

2×{Ag+(aq)+1e−→Ag(s)} Eo=0.80 V (Cathode)
Ni(s)→Ni2+(aq)+2e− Eo=0.23 V (Anode)
 −−−
2Ag+(aq)+Ni(s)→Ni2+(aq)+2Ag(s) Eocell=1.03 V

Start with the anode components (site of oxidation) - the cathode components are listed to the right.

Ni(s)∣∣Ni2+(aq) ∣∣∣∣ Ag+(aq)∣∣Ag(s)

The single vertical lines indicate the boundary (phase difference) between solid Niand Ni2+ ions in the aqueous solution of the first compartment and between solid Ag and Ag+ ions present in the aqueous solution of the second compartments.

The double vertical lines refer to the salt bridge - note that the salt bridge must be an inert salt to both ions present in both compartments of the galvanic cell ...

5 0

3 years ago

How would you define what the conductivity of a substance is?

iragen [17]

Answer:

Conductivity of a substance is defined as 'the ability or power to conduct or transmit heat, electricity, or sound'.

Explanation:

hope it helps

plzz mark as brainliest....

7 0

3 years ago

How do you write a polynomial in standard form?

olchik [2.2K]

One way to write a polynomial is in standard form. In order to write any polynomial in standard form, you look at the degree of each term. You then write each term in order of degree, from highest to lowest, left to write. First, look at the degrees for each term in the expression. and in this way you will be able to write polynominal in standard form.

8 0

3 years ago