# What mass of water is produced when 8.0g of hydrogen reacts with…

##### Admin

## What mass of water is produced when 8.0g of hydrogen reacts with excess oxygen?

**A.** 8.0g

**B.** 16.0g

**C.** 36.0g

**D.** 72.0g

**QUICK ANSWER…**

D

**DETAILS…**

**To resolve this, we must write out the balanced equation thus: 2H₂ + O₂→ 2H₂O**

**From this balanced equation we can infer that:**

**2 moles of hydrogen is required to form 2 moles of water**

**Now, we have to determine how many moles of hydrogen is equivalent to a mass of 8g**

**2g of H****₂**** = 1 mole, therefore,**

**8g of H****₂**** = x mole.**

**Cross multiplying to solve for x, we have:**

**2x = 8**

**x = 8/2 = 4moles**

**this implies that 4 moles of hydrogen is present.**

**Now, if from the balanced equation,**

**2 moles of H₂ forms 2 moles of H₂O, then**

**4 moles of H****₂**** will form Y moles of H****₂O**

**Cross multiplying to find Y, we have:**

**2Y = 4(2)** = 8

**Y = 8/2 = **4

**This implies that the number of moles of water formed = 4 moles.**

**Now converting these 4 moles of water to grams, we have:**

**Molar mass of H****₂****O = 2 + 16 = 18g**

**This implies that 1 mole of H****₂****O = 18g, therefore,**

**4 moles will be = 4 × 18 = **72g

### SHORT-CUT

There’s a short cut solution,

using the balanced equation,

mass of **2H₂** = 2(2) = 4g

mass of **2H₂O** = 2(2+16) = 2(18) = 36g

this implies that:

4g of hydrogen gas produces 36g of water, therefore,

8g of hydrogen gas will produce X

cross multiplying to solve for X, we have:

X(4) = 8(36)

X = (8 **×** 36)/4 = 72g

**Now for the right answer to the above question:**

**Option A is incorrect.****Option B is incorrect.****C is incorrect.****D is the correct answer.**

**KEY-POINTS…**

**You may please note these/this:**

**For accuracy and clarity purposes, you must write out the balanced chemical equation of questions like this.****The importance of writing out the balanced equation is to properly understand the mole ratios involved, and to make your assumptions properly.****If you love our answers, you can login to say hi to us at the comment section…**

**To raise new related question****s, c****lick the ASK A QUESTION BOTTON down this page…**

**/ culled from 2020 JAMB-UTME chemistry past question 32 /**

##### What mass of water is produced when 8.0g of hydrogen reacts with... » QuizTablet

CHEMISTRY SHORT-CLASS!!!

**Course Provider: **
Organization

**Course Provider Name: **
N.D Sammy

**Course Provider URL: **
QuizTablet.com

**Editor's Rating:**

8