ld: library not found for -lgcc_ext.10.5

I'm trying to compile a basic C++ program for school and when I try running it from the Mac Terminal (10.7.6), I get this message:

ld: library not found for -lgcc_ext.10.5
collect2: error: ld returned 1 exit status

I'm definitely in the correct directory and installed XCode Command Line tools. Here is my command prompt:

g++ -o chapter_2 hello_world.cpp

Here is my basic c++ program.

#include <iostream>

using namespace std;

int main(){

  cout << "Hello world" << endl;

}